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Inference to the Best Explanation: A Common and Effective Form of ArchaeologicalReasoningAuthor(s): Lars FogelinSource: American Antiquity, Vol. 72, No. 4 (Oct., 2007), pp. 603-625Published by: Society for American ArchaeologyStable URL: http://www.jstor.org/stable/25470436 .Accessed: 19/03/2011 02:46
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INFERENCE TO THE BEST EXPLANATION: A COMMON AND EFFECTIVE FORM OF ARCHAEOLOGICAL REASONING
Lars Fogelin
Processual and postprocessual archaeologists implicitly employ the same epistemological system to evaluate the worth of
different explanations: inference to the best explanation. This is good since inference to the best explanation is the most
effective epistemological approach to archaeological reasoning available. Underlying the logic of inference to the best expla nation is the assumption that the explanation that accounts for the most evidence is also most likely to be true. This view of
explanation often reflects the practice of archaeological reasoning better than either the hypothetico-deductive method or
hermeneutics. This article explores the logic of inference to the best explanation and provides clear criteria to determine
what makes one explanation better than another. Explanations that are empirically broad, general, modest, conservative,
simple, testable, and address many perspectives are better than explanations that are not. This article also introduces a sys tem of understanding explanation that emphasizes the role of contrastive pairings in the construction of specific explana tions. This view of explanation allows for a better understanding of when, and when not, to engage in the testing of specific
explanations.
Arqueologos de las orientaciones teoricas procesualy postprocesual, implicitamente emplean el mismo sistema epistemologico
para evaluar el merito de diferentes interpretaciones: inferencia a la mejor explicacion. Esto es bueno ya que inferencia a la
mejor explicacion es el metodo epistemologico mas efectivo del razonamiento arqueologico disponible. Fundamental a esta
logica es la suposicion de que la explicacion que incorpora la mayor evidencia es tambien la mas probable de ser verdad. Este
metodo de explicacion refleja mas correctamente la prdctica real del razonamiento arqueologico comparado con el metodo
hipotetico-deductivo o la hermeneutica. Este ensayo explora la logica de la inferencia a la mejor explicacion y proporciona criterios claws para determinar que hace una explicacion mejor que otra. Las explicaciones que son empiricamente com
prensivas, generales, modestas, conservativas, simples, que son refutables y que hacen referenda a multiples perspectivas son
mejor que las explicaciones que no lo son. Este ensayo ademds introduce un sistema para el entendimiento de explicaciones
que acentua elpapel que juegan pares contrastantes en la construccion de explicaciones especificas. Esta perspectiva de expli cacion permite un mejor entendimiento de cuando, y cuando no, es necesario probar explicaciones especificas.
This article begins with a simple observation.
Whatever theoretical perspectives archaeol
ogists have brought to their research, they have often created long-lasting, powerful explana
tions concerning the lives of people in the past. I am
not suggesting that all archaeological research has
been good?some has been terrible?but through
out all the differing perspectives and approaches in
archaeology, a steady output of compelling, seem
ingly right, explanations of the past have emerged. How has all this good research been possible?
This may seem an odd question. However, when
viewed against the backdrop of archaeological the
ory, it is an important one. At two points in archae
ology's recent disciplinary history, theoretical rev
olutions are said to have occurred: first in the 1960s
with the new archaeology (later termed processual
archaeology) and again in the 1980s with post
processual archaeology. In both cases, proponents claimed that new approaches to archaeology that
signified a radical break with the past were being
developed. If the rhetoric of the rival camps is taken
seriously, processual and postprocessual archaeol
ogists were engaged in wholly different enterprises and should not have been able to have any pro ductive discourse.1 At first glance, the proces
sual/postprocessual debates would seem to fit this
characterization well. However, today many
Lars Fogelin Department of Anthropology and Sociology, Albion College, 611 East Porter St., Albion, MI 49224
(LFogelin@Albion.edu)
American Antiquity, 72(4), 2007, pp. 603-625
Copyright ?2007 by the Society for American Archaeology
603
604 AMERICAN ANTIQUITY [Vol. 72, No. 4,2007
archaeologists, myself included, claim to work in
the middle ground between these two archaeolog ical perspectives. Archaeologists of a more empiri cist bent talk of doing "processual plus"
archaeology (Hegmon 2003). Those with more
interpretive leanings are actively engaging in field
work and re-embracing many of the "scientific"
methodologies pioneered by the new archaeology. In the meantime, both sides borrow data from one
another and continue to rely on the work of archae
ologists from the early twentieth century. How has
all of this been possible? How do archaeologists balance two supposedly irreconcilable perspec tives? How is it that the data and knowledge pro
moted by these two perspectives are usable in the
other? If processual and postprocessual archaeol
ogy are truly as incompatible as their proponents once claimed, no synthesis should be possible. Yet
it is occurring. My explanation is straightforward. Neither processual nor postprocessual archaeology are as different from each other as their practition ers claim. They have each brought new concerns
and questions to archaeological inquiry, but both
often rely implicitly on the same underlying style of reasoning?inference to the best explanation.
Making an inference to the best explanation is, at its heart, a straightforward and common process.
According to Lipton (1991:58), "Given our data
and background beliefs, we infer what would, if
true, provide the best of the competing explanations
we can generate of those data." One additional point
is critical. The ability of an explanation to explain a wide variety of data makes it more likely to be true. Clearly, this is a problematic statement in
terms of the official epistemologies of processual and postprocessual archaeology. I ask, for the
moment, that readers reserve judgment on these
epistemological issues and consider how they actu
ally engage in archaeological research. All systems of reasoning have their own sets of epistemologi cal problems. The question then is not which sys tem of reasoning can or cannot provide some
measure of objective truth, but rather, which one is
most useful in terms of archaeological research.
This article has three interlocking goals. First, I
define what inference to the best explanation is and
show how it works. Second, I argue that inference
to the best explanation has been "standard practice" in archaeology for over a century. Its implicit use
partially accounts for much of the best work that
archaeology has to offer. This article is not a
detached discussion of the philosophy of science.
It is intended to be a practical guide for improving
archaeological research. For this reason, this arti
cle concludes with several straightforward sug
gestions toward improving upon the implicit use
of inference to the best explanation in archaeology.
Following Wylie (2002:25-41), I recognize that
the social theories and perspectives of archaeolo
gists have been widely divergent.2 The argument
presented here is only that the underlying standards
used to assess archaeological explanation are
largely the same throughout much of archaeology. The larger social theories that inform these expla nations are often at odds with one another in pro found and important ways. These differences
should not be minimized. Even if my suggestions
concerning inference to the best explanation are
widely accepted, archaeologists will find no lack
of issues to debate.
Philosophy of Science in Archaeology
With the advent of the new archaeology in the
1960s, archaeologists began a process of explicitly
addressing epistemological questions. It was
argued that archaeology should employ the scien
tific method, initially understood as a deductive
nomological enterprise as described by Hempel (covering law model: Hempel 1965, 1966).3
Archaeologists were advised to develop laws of
culture, create testable hypotheses, and apply them
through deduction to the archaeological record
(Binford 1967, 1968a, 1968b; Binford and Bin
ford, eds. 1968; Fritz and Plog 1970; Hill 1970; Watson etal. 1971,1984).
Following the standard definition of deduction
in philosophy, Hempel (1966:10) stated that "in a
deductively valid argument, the conclusion is
related to the premises in such a way that if the
premises are true then the conclusion cannot fail to
be true as well."4 At first glance this definition might seem to imply that any valid deduction must yield true results. That is incorrect. Given the standard
definition of deductive validity, it is possible for a
valid deductive argument to have a false conclu
sion, for example:
All hominids have wings. Homo ergaster is a hominid.
Thus, Homo ergaster has wings.
Fogelin] INFERENCE TO THE BEST EXPLANATION 605
This is a valid deduction because if the premises were true then the conclusion would have to be true
as well. Of course, both the first premise and the
conclusion are false, but that does not affect the
deductive validity of the argument. In fact, this is
a pattern of reasoning commonly used in science
to refute proposed universal statements or laws. If
Homo ergaster is a hominid and specimens of
Homo ergaster do not have wings, then we can
validly reason that not all hominids have wings. This simple point of logic lies at the heart of the
hypothetico-deductive method Hempel advocated
for testing scientific hypotheses. For Hempel, those hypotheses that fail a valid
deductive test must be rejected or at least modified.
Conversely, those hypotheses that survive multiple tests are taken to be stronger (Hempel 1966:8). For
Hempel, this measure of strength is derived from
inductive reasoning, not deductive reasoning.
Hempel is explicit on this point.
Even extensive testing with entirely favorable
results does not establish a hypothesis con
clusively, but provides only more or less strong
support for it. Hence, while scientific inquiry is certainly not inductive in the narrow sense
... it may be said to be inductive in a wider
sense, inasmuch as it involves the acceptance
of hypotheses on the basis of data that afford no deductively conclusive evidence for it, but
lend it only more or less strong "inductive sup
port," or confirmation [Hempel 1966:18;
emphasis in original].
While it is possible for a scientist to assess
whether a deduction is valid, it is not logically pos sible to state with certainty that any of its premises are irrefutably true. The latter would, as noted by
Hempel (1966:7), fall into the fallacy of affirming the consequent. Thus, deduction by itself has no
mechanism to establish any form of independent or objective truth.
The deductive-nomological approach, as under
stood by Hempel, required that a set of universal
laws of human behavior be developed in archaeol
ogy. By the mid-1970s, even some of Hempel's strongest advocates recognized that little progress
was being made in the creation of these laws (Bin ford 1977;Flannery 1973; Read and LeBlane 1978;
Tuggle et al. 1972; Watson et al. 1984). Forty years later, it does not appear that laws of human behav
ior are any closer to being developed, and few
archaeologists are even trying (see also LaMotta
and Schiffer 2001; Schiffer 1988). With the recognition of the limitations of the
deductive-nomological approach, archaeologists and philosophers began searching for a philosophy of science more appropriate for archaeology. Mer
ilee and Wesley Salmon advocated approaches that
could account for the statistical nature of archaeo
logical reasoning (Salmon 1982; Salmon and
Salmon 1979). Others promoted the falsification
strategy of Karl Popper, arguing that hypotheses can never be confirmed, only rejected (Peebles 1992; Popper 1959, 1976). Others mined biology
and geology for scientific methods deemed more
appropriate for historical sciences (Dunnell 1989,
1992; Flannery 1986; Lyman and O'Brien 1998). Some strayed further from the hypothetico deductive fold, appropriating philosophical dis
cussions of realism (Gibbon 1989) or even rejecting
outright the need for scientific positivism in archae
ology at all (Hodder 1982,1983,1984; Shanks and
Tilley 1987a, 1987b). With the exception of the
anti-positivist outlook of postprocessual archaeol
ogy, few of the alternative systems appear to have
caught on. For the most part, archaeologists seem
to have gone about their research without a clearly articulated epistemological foundation. While some processual archaeologists make vague claims
to the hypothetico-deductive method, in practice it seems that hypotheses are becoming rarer-and-rarer
in the archaeological literature. This point can be most clearly seen in Hegmon's (2003:230) recent discussion of processual-plus archaeology, where
the hypothetico-deductive method is discussed
mostly for its historical interest. Given the quantity and diversity of philosophi
cal writings in archaeology, it is not possible to pro vide a detailed review of them here. Other reviews are more than adequate for this purpose (Gibbon 1989; Kelley andHanen 1988; O'Brien etal. 2005;
Wylie 2002; see also Bawden 2003). However, a
few archaeological discussions of epistemology bear directly on the arguments presented here. In
the background of the epistemological debates in
archaeology, several archaeologists and philoso
phers have argued that little has actually changed? that most archaeologists continue to employ the same sorts of reasoning they always have. Peter
Kosso (1991; see also Arnold 2003) has argued
606 AMERICAN ANTIQUITY [Vol. 72, No. 4,2007
that the middle-range theory of processual archae
ology and hermeneutics of postprocessual archae
ology are, in practice, pretty much the same.
Christine VanPool and Todd VanPool (1999,2001; see also Arnold and Wilkens 2001; Hutson 2001;
Wylie 2002:200-210) have gone further, arguing that postprocessual archaeology is just as scientific
as processual archaeology. One common problem unites all of these articles. What do archaeologists
gain from the recognition of these fundamental
similarities? How does it improve archaeological research? The recognition that archaeological rea
soning across the discipline is similar should lead
to specific suggestions for improving research.
To date, inference to the best explanation has
played only a small role in archaeological discus
sions of epistemology. The most explicit use of the
concept can be found in Marsha Hanen and Jane
Kelley's "Inference to the Best Explanation in
Archaeology" (1989; see also Kelley and Hanen
1988). Here Hanen and Kelley employed the con
cept of inference to the best explanation to argue that the underlying styles of reasoning of proces sual and earlier forms of archaeology were funda
mentally similar. They contrast Kelley's processual research at Cihuatan, El Salvador (Hanen and Kel
ley 1989) with Emil Haury's (1958) research at
Point of Pines in the American Southwest. They concluded that both archaeologists evaluated mul
tiple explanations for a given phenomena, in the
end accepting the 'best' explanation as most likely to be true. The best explanation, in their view, was
determined by eliminating explanations that were
"less well supported" by the material evidence
(Hanen and Kelley 1989:16). In terms of their
analysis of specific cases, I am in full agreement with Hanen and Kelley. Further, I will argue that
postprocessual archaeologists also employ infer
ence to the best explanation in a similar fashion.
My concern with Hanen and Kelley's discussion is
what it does not address. It does not provide a clear
definition of inference to the best explanation, nor
does it present clear guidelines for how to evaluate
which explanation is best. Further, even if one
explanation is shown to be best, there is no guar antee that the explanation is any good. It might
simply be the best of a bad lot. Any application of
inference to the best explanation in archaeology
requires methods to reject those "best" explanations that are not "good" explanations.
Induction
If we take as a starting point the limitations of the
hypothetico-deductive method in archaeological
reasoning, it would seem that archaeological expla nations must often be derived from either flights of
fancy or some form of inductive reasoning. As for
the former, it would not account for the observa
tion that began this article?that a great deal of
good, seemingly right, research has occurred in
archaeology. This suggests that induction must be
involved in a great deal of good archaeological rea
soning. The difficulty is that none of the standard
systems of induction seem to fit many of the forms
of explanation that archaeologists typically employ. This section examines traditional types of induc
tion to demonstrate (1) that they could not produce the explanations commonly constructed by prac
ticing archaeologists, and (2) that traditional forms
of induction often rely implicitly on inference to
the best explanation. As defined by The Oxford Companion to Phi
losophy (Honderich, ed. 1995:405), "an inductive
inference can be characterized as one whose con
clusion, while not following deductively from its
premises, is in some way supported by them or ren
dered plausible in light of them." In contrast to a
valid deduction, the conclusion of an inductive
argument can be false even if the premises are true.5
Induction can occur from specific cases to general
principles and, despite a common misunderstand
ing, from general principles to specific cases.6 The
most important element of inductive arguments is
that they are ampliative.7 That is, their conclusions
contain more information than is contained within
their premises. This is a very valuable trait. To use
a classic example, on observing many black ravens,
I might infer that all ravens are black. Here I have
amplified my limited number of observations of
black ravens to a general statement about raveness
(they are all black). Central to all forms of induction lies a critical
assumption, first identified by David Hume
(1956[1777])?regularities that have occurred in
the past will continue to occur in the future. If the
sun has risen every day, it will continue to do so
tomorrow. Inductions, then, are always underde
termined by empirical evidence. As in the exam
ple above, they are empirical generalizations from
a limited sample of past experiences. Further, there
Fogelin] INFERENCE TO THE BEST EXPLANATION 607
always remains the chance that the sun will not con
tinue to rise in the future (for example, when it
explodes 5 billion years from now). All inductive
arguments, no matter how robust, are always sub
ject to rejection with the discovery of new infor
mation. This problem with induction is often
referred to as Hume's skepticism concerning induc
tion. The conclusions of an inductive argument are
always under threat of the discovery of new evi
dence that could discredit them.
Humean skepticism is not the only form of skep ticism that archaeologists must face. Cartesian
skepticism serves as the epistemological founda
tion of many of the postmodern ideas that under
write postprocessual archaeology. This form of
skepticism is not based on the limits of inductive
reasoning, but rather the unreliability of sensory information. Cartesian skeptics claim that the world
outside our own mind can never be known objec
tively because our sensory perception is epistemo
logically unreliable. Building on this argument, Kant (1998[1781]) proposed that people cannot
simply perceive an objective world; instead, they
actively construct it. In this way, Kant serves as the
bridge between Cartesian skepticism and the con
structivist theories that inform postprocessual
archaeology. Specifically, Cartesian skepticism is
the foundation for claims that knowledge is con
ditioned by the social, political, and historical con
text of the observer. In the end?through an entirely different route?Cartesian skeptics reach the same
skeptical doubts concerning objective claims about external phenomena, more-or-less, as Humean
skeptics do. It is important to note that these skep tical doubts do not apply only to archaeological claims about the past, but to any claim about any
thing outside the mind of an individual. I cannot resolve either of these skeptical prob
lems. I doubt anyone can. There is simply no way
to rule out the possibility that current regularities
might change in the future or that our senses pro vide unreliable information about the world. The
evaluation of different forms of reasoning, there
fore, cannot be based on the ability of a system of
reasoning to objectively identify irrefutable truths.
Any claim or explanation about the world?past or
present?requires a violation of absolute logical or
epistemological ideals. The question is which stan dards to violate, and how? Rather than relying upon an
epistemological guarantee of truth, archaeolo
gists must employ more flexible, practical criteria
based upon their experience in constructing and
evaluating arguments to make these determina
tions. More simply phrased, archaeologists need to
examine which violations of absolute epistemo
logical ideals lead to explanations that seem to work
over the long term. A successful example of this
can be seen in the hypothetico-deductive approach when Hempel argued that hypotheses that survived
multiple attempts at falsification could serve as
widely accepted laws.
Philosophers have identified several different
types of induction. These include: analogical infer
ence, statistical induction, and inference to the best
explanation. Perhaps the most ink has been spilled in archaeology over analogical reasoning (Ascher
1961;Binford 1967; Gould and Watson 1982). This
form of reasoning is covered well, in my opinion,
by Alison Wylie (2002:136-153). Analogical rea
soning follows a simple structure: if A is composed of a set of traits (Al, A2, A3...), and B shares those
traits (Bl, B2, B3...), plus others (B4 and B5), it
follows that A might also have those traits (A4 and
A5). Wylie notes the general philosophical under
standing that good analogical arguments also note
the points of dissimilarity. Further, Wylie (2002:147-148) argues that strong "analogical
comparisons generally incorporate considerations of relevance that bring into play knowledge about
underlying 'principles of connection' that structure
the association of properties in the source and the
subject." I will argue that strong analogical argu ments also employ inference to the best explana
tion. The assumption of analogical reasoning is that some principle of connection exists between the traits being compared. In a strong use of analogi
cal reasoning, this relationship is explained. In a
weak analogical argument, the relationships are
left unexplained (though assumed to exist). Ana
logical reasoning, on its own, cannot create prin
ciples of connection that link the traits being studied. As will be discussed below, this is the job of inference to the best explanation. Thus, strong
analogical arguments employ inference to the best
explanation to clarify the relationships between the traits selected for comparison.
Statistical induction is what most people think of when they consider inductive reasoning.8 The discussion of ravens above is a classic example of
statistical induction. On seeing a sample of the total
608 AMERICAN ANTIQUITY [Vol. 72, No. 4,2007
population of ravens, an empirical claim concern
ing the rest of them is proposed (they are all black). The most obvious standard employed to judge the
quality of a statistical induction is the quantity of
prior observations. A statistical induction based on
a few raven sightings would be weaker than one
based on thousands of raven sightings. Statistical
inductions are also stronger, in practice, with
increased temporal and geographic diversity in the
observations. Archaeologists regularly employ these criteria when they examine inductive argu
ments. But archaeologists often run into problems at this point. When archaeologists evaluate infer
ences concerning the Pyramids of Giza, how many other massive, awe-inspiring pyramid complexes
along the Nile can they observe? Sadly, this is not
the only problem with statistical induction in terms
of archaeological research.
Let's suppose that I am an archaeologist study
ing domestic architecture.91 have excavated many domestic structures and read the reports of other
excavations. It is now time to infer something. I first
decide to make a highly universal empirical
generalization?all domestic structures have some
sort of entrance. On the face of it, this does not
appear particularly illuminating. It brings to mind
Flannery's (1973:51) oft-cited critique of "Mickey Mouse laws." By sacrificing universality, I might be able to state something more interesting?most domestic structures contain a hearth. This conclu
sion, while still not earth-shaking, at least allows
for some ideas of where and how food preparation occurred. Finally, let's compare these examples
with the results of a real archaeological study of
domestic architecture, in this case Colin Richards's
(1990) examination of Neolithic semi-subterranean
houses in the Orkneys. In Richards's (1990) study, he examined the lay
out and organization of different features within the
houses in relation to one another. Where is the
hearth in relation to the door, in relations to the beds, in relation to cooking areas, etc.? Through these
examinations Richards identified several nested
oppositions in the use of space. First, he identified
a general right/left division of space within the
houses in relation to the door. Since the doors of
the houses enter toward the right side of the house
and provide greater illumination to that side,
right/left can also be read as interior/exterior and
light/dark. By identifying gendered activities in the
two areas, a male/female dichotomy was also
found. Finally, Richards related the organization of
houses in the Orkneys to Neolithic cosmological
principles connected to seasonal changes. Where did all that come from? It certainly does
not appear to be a statistical induction of the form
noted above, nor do I believe Richards intended it
be. First, Richards's sample is small. The richness
of his explanations cannot be explained by his sam
ple size. Second, the explanation seems different
from the empirical generalizations that typically result from statistical induction. Rather than mak
ing a general statement about houses, he provides an interpretation that brings distinct elements of
these particular houses within an overarching
understanding. Richards's explanation may be
wrong. New information might overturn his con
clusion. For example, archaeologists might learn
that traditional gender roles were reversed or absent
in the Orkneys during the Neolithic. This only goes to show that whatever Richards is doing, it must be
a form of induction. But just as clearly, it is not sta
tistical induction.
Some might suggest, incorrectly I argue, that the
richness of Richards's explanation was due to an
underlying, complex set of statistical inductions. By
employing many statistical inductions (concerning issues of gender, cooking patterns, concepts of
lighting, cosmology, etc.) their roles in Richards's
explanation were disguised. This, however, brings
up a final difficulty with statistical induction. As
the number of premises of a statistical induction
increase, the reliability of its conclusions decrease.
This can be viewed as the problem of multiplying error. All of the premises of a statistical induction can be discredited with new information. Some, or
all, may also be wrong. If it later turns out that one
of the premises is wrong, or at least not wholly right, faith in the conclusion is reduced. The more
premises employed, the greater the chance that this
might occur. Despite archaeologists' widely held
conviction that multiple lines of evidence improve an argument, in terms of statistical induction they do not. This does not mean that multiple lines of
evidence do not have value. They do. Rather, sta
tistical induction does not provide a venue in which
the value of multiple lines of evidence can be effec
tively accounted for.
To sum up, statistical induction has several
inherent problems. First, it is always subject to
Fogelin] INFERENCE TO THE BEST EXPLANATION 609
rejection based upon new evidence. Inference to the
best explanation does nothing to solve this prob
lem; but if Hume is right, no system of reasoning does. Statistical inductions are also highly depen dent upon the quantity and diversity of previous observations. For this reason, it does not address
particularities in the past well at all. Finally, statis
tical induction does not have a mechanism to
account for the value of multiple lines of evidence.
It is in regard to these latter problems that infer ence to the best explanation is an advance over sta
tistical induction. Inference to the best explanation
places epistemological value on multiple lines of
evidence and can accommodate explanations of
unique phenomena.
Inference to the Best Explanation
Elements of inference to the best explanation can
be found in the writings of Peirce (1931) and other
pragmatic philosophers (Dewey 1929; Hanson
1958; Mill 1904). For these philosophers, inference to the best explanation (what Peirce called abduc
tion or retroduction) was thought to characterize
the creative process that scientists used to gener ate hypotheses. Peirce correctly noted that prac
ticing scientists did not simply observe
commonalities and make empirical generalizations. Rather, scientists sought to explain surprising observations by creating explanations that would account for them. More formally, if a proposed
explanation made a surprising phenomenon explic able, there was sufficient reason to think it might
be true. Peirce saw inference to the best explana
tion as a way to develop strong hypotheses for sub
sequent investigation through standard forms of
scientific reasoning. In Peirce's formulation, then,
inference to the best explanation was viewed as a
model for the initial creative process of scientific
inquiry. In the 1960s and 1970s, Gil Harman developed
the understanding of inference to the best expla nation that underlies this discussion (Harman 1965, 1968a, 1968b, 1973; see also Brody 1970; Hanson
1958; Lipton 1991; Thagard 1978). As presented by Harman (1965:89), when conducting inference to the best explanation, "one infers, from the
premise that a given hypothesis would provide a 'better' explanation for the evidence than would any
other hypothesis, to the conclusion that the given
hypothesis is true." Thus, it is assumed within infer
ence to the best explanation that the best inference
is also most likely to be true.10 The key difference
between Harman's and Peirce's formulations is the
recognition that inference to the best explanation is not only limited to the initial stages of scientific
reasoning. In practice, inferences to the best expla
nation can be sufficiently robust as to be accepted as true without further testing or investigation what soever. At times, some hypotheses are stronger at
inception than those that have been subjected to
numerous rounds of rigorous testing.
At first glance, inference to the best explanation may seem absurdly circular. It actually isn't. Prov
ing that one explanation is "more true" than another
would require prior knowledge of the "true" expla nation. Even if it was possible, we would have to
wonder why anyone would be evaluating the rela tive truth of explanations for a particular set of evi dence if he or she already had the perfect explanation in hand. Still, there must be criteria to
judge which explanations are best for inference to
the best explanation to work. Rather then judging an explanation based upon its likeliness, an infer ence to the best explanation should be evaluated in terms of how compelling it is (Lipton 1991: chap ter 7).11 Compelling explanations have traits that
people have found to characterize successful expla nations in a wide variety of contexts. Many of these traits are already familiar to archaeologists. For
example, accounting for a greater quantity and
diversity of empirical evidence will typically make an argument more compelling. Similarly, all things being equal, a simpler explanation is usually viewed as being more compelling than a complex explana tion. I examine, in detail, toward the end of this arti
cle, several of the traits that philosophers have identified as characterizing compelling explanations.
People employ inference to the best explanation almost constantly with little thought about the sys tem of reasoning they are engaging. A mechanic
employs it to diagnose the problem with a car. A detective uses it to decide who committed a crime. The central element of inference to the best expla nation is that it searches for that explanation that fits the diverse evidence available. Inference to the best explanation is, perhaps, most clearly demon strated in detective stories. The fictional detective links the diverse, if not bizarre, evidence into a sin
gle explanation that clearly indicates that only one
610 AMERICAN ANTIQUITY [Vol. 72, No. 4,2007
of a group of people is the culprit. While more
complex than most inferences to the best explana tion, detective novels serve to illustrate a form of
reasoning that pervades our everyday lives.
As argued by Harman (1965) and Lipton (1991), inference to the best explanation effectively addresses some of the limitations of statistical
induction. First, and perhaps most important for
archaeology, it allows for the development of expla nations for unique or infrequent archaeological
phenomena. It does this by placing epistemologi cal value on multiple lines of evidence. While
strengthened by application in multiple cases, infer
ence to the best explanation also focuses on the abil
ity of an explanation to account for the diversity of
evidence in specific cases. That explanation which
accounts for the greatest diversity of evidence is
assumed most likely to be true, even where that case
is unique.
The second benefit of inference to the best expla nation is that it allows for the construction and eval
uation of explanations, not just the identification of
empirical generalizations or regularities. An infer
ence to the best explanation details the relationships between divergent evidentiary elements. In a sense, it makes elements thought to be independent lines
of evidence dependent upon one another. Using
Wylie's terms concerning analogical arguments,
inference to the best explanation details the "prin
ciples of connection" between the available evi
dence (Wylie 2002:147-148). In this sense, inference to the best explanation provides answers
to "why" and "how" questions rather than simply
noting empirical regularities. A fundamental confusion lies at the heart of
many discussions of the philosophy of science. Sci
ence does not have a monopoly on reasoning. For
example, in examining Shakespeare's Macbeth, I
might ask if Macbeth is a good, but weak, charac
ter tempted toward regicide by Lady Macbeth, or
an evil, but cowardly, character given backbone by
Lady Macbeth? To address this question I could
employ several lines of evidence: I could examine
specific scenes within Macbeth, I could study
Shakespeare's other plays and sonnets to see his
general approach toward this sort of issue, or I
could even consider general beliefs concerning
good and evil, husbands and wives, and regicide
during Elizabethan England. While potentially
employing well-reasoned argumentation, including
inference to the best explanation, no analysis of
Macbeth could be considered scientific by any con
ventional definition.
Despite what some scientists and even a few
humanists say, well-reasoned arguments exist
throughout the humanities. When historians study the past, they do not simply make it up; they make
arguments and employ reasoning to generate expla nations about the past or present. Other historians
evaluate their arguments, and accept, reject, or mod
ify them accordingly. Bad reasoning and research
exist in every discipline, but clearly there are also
standards for acceptance and rejection. As I will
argue below, inference to the best explanation is one
of these standards. While inference to the best
explanation is used in the sciences, it is not limited
to the sciences. Thus, the use of inference to the
best explanation is unrelated to questions con
cerning the proper role of scientific reasoning in
archaeology.
Below I provide several examples of the use of
inference to the best explanation in archaeological research. These examples serve two functions.
First, the examples further illustrate how inference
to the best explanation works. Second, they also
suggest its ubiquity in archaeological reasoning.
The Ubiquity of Inference to the Best
Explanation in Archaeological Reasoning
A strong demonstration of the pervasiveness of
inference to the best explanation in archaeological
reasoning would require examining a large sample of archaeological research and determining the rel
ative frequency of its application?in essence the
use of statistical induction. There is not sufficient
time or space to do this here. Instead, I examine
four specific archaeological studies and discuss the
manner in which inference to the best explanation is embedded within their respective arguments.
These cases are Alfred Kidder's (1924) explana tions of pueblo aggregation, Lewis Binford's (1967)
study of smudge pits, Ian Hodder's (1991) discus
sions of hermeneutics, and Michelle Hegmon and
Wenda Trevathan's (1996) analysis of Mimbres
birth scenes.
Alfred Kidder
In Southwestern Archaeology (1924), Alfred Kid
der proposed that the shift from small, independent
Fogelin] INFERENCE TO THE BEST EXPLANATION 611
unit pueblos of the Pueblo I period to the large cen
tralized pueblos of the Pueblo period in the San Juan
Basin was the result of "hostile pressure" from a
"nomadic enemy" (Kidder 1924:126-127). Kidder
argued that the need for defense against these hos
tile nomads forced the abandonment of peripheral settlements and the aggregation of pueblo people into larger house blocks. Kidder contrasted his
explanation for pueblo aggregation with another:
that aggregation was the result of the progressive desiccation of the southwestern environment, forc
ing pueblo people into more restricted areas
(Hewett et al. 1913; Huntington 1914). In evaluat
ing the two potential explanations, Kidder stated:
To begin with, many of the districts which were
shortly abandoned are still among the most
favorable as to water supply in the entire South
west; secondly, many peripheral ruins (as in
western Utah and eastern New Mexico) were
seemingly deserted at an early time; lastly, the
more recent villages are larger, stronger, and
occupy more easily defensible sites, than the
older ones [Kidder 1924:126].
In Kidder's view, then, his explanation accounted for the observed chronological patterns of site abandonment in the peripheries, the aggre
gation of pueblo people in the core of the San Juan
Basin, and the architectural form of the resulting
larger pueblos. The desiccation explanation, in con
trast, failed to account for the observed patterns of
water availability, the known chronology of pueblo abandonment, or the form and location of subse
quent aggregated pueblos. "I stress here, as before,
the influence of the nomadic enemy; for this
appears to me best to explain the observed facts of
Pueblo history" (Kidder 1924:127). Kidder, implic
itly following the principles of inference to the best
explanation, inferred that the explanation that
accounted for the greatest diversity of evidence was
more likely to be true. Kidder (1924:128) also rec
ognized that the "question is still an open one,"
showing that whatever form of reasoning he
employed, it must have been inductive. Despite later criticisms of cultural-historical archaeology (e.g., Binford 1962, 1968a; Taylor 1948), Kidder
was not simply engaged in description, and the sys tem of reasoning he employed was, and still is,
among the best available to practicing archaeolo
gists. The errors of his explanation are not the prod
uct of epistemological issues, but rather the limited
archaeological evidence at his disposal.
Lewis Binford
As presented by Lewis Binford (1967), "Smudge Pits and Hide Smoking: The use of Analogy in
Archaeological Reasoning" was intended to illus
trate how analogy could be effectively employed within a deductive-nomological approach to
archaeological reasoning. Binford used an analy sis of a particular type of archaeological feature
common in the Eastern United States, smudge pits for hide smoking, to illustrate his argument.
Smudge pits are small holes containing burnt mate
rial (corncobs, twigs, and other vegetable mater
ial), with the upper portion of the pit often covered
loosely with soil (Binford 1967:3-4). I argue that
rather than exemplifying the deductive
nomological approach, Binford's analysis of
smudge pits implicitly employs inference to the
best explanation in much the same way as Kidder
did.
Based upon the close correspondence between
the ethnographically described smudge pits and the
archaeological features, Binford (1967:8) "postu lated that the archaeologically-known features were
in fact facilities employed in the task of smoking hides by the former occupants of the archaeologi cal sites on which they were found." The key term
here was "postulated." Following the deductive
nomological approach of Hempel, "the final judg ment of the archaeological reconstruction... must
rest with testing through subsidiary hypotheses
drawn deductively" (Binford 1967:10). What is
odd, however, is that Binford never tested his pos tulate, nor were his subsidiary hypotheses drawn
from valid deductions.
Binford proposed, but never tested, three
hypotheses based upon further readings of the
ethnographic literature. One of these hypotheses was that "smudge pits should occur in 'base camps'
occupied during the period of the year when hunt
ing activity was at a minimum" (Binford 1967:9). This is not a valid deduction. As discussed earlier, in a valid deduction the conclusion must necessar
ily follow from its premises. In a valid deduction, a
single piece of contradictory evidence falsifies the
hypothesis. The failure to find smudge pits at a sin
gle base camp would be sufficient to negate the
hypothesis. Yet, as Binford himself noted (1967:9),
612 AMERICAN ANTIQUITY [Vol. 72, No. 4,2007
the ethnographic literature indicates that hide smok
ing was performed by specialists. The absence of
smudge pits, therefore, might only show that no
hide smoking was performed at a particular base
camp because the group living there did not include a hide smoking specialist at the time that the base
camp was occupied. Thus, if we accept Binford's
identification of these features as smudge pits for
hide smoking, it cannot be due to his use of the
hypothetico-deductive approach advocated by
Hempel. His hypotheses were not validly deduced
and he never tested them in any case. Rather, Bin
ford seemed satisfied with his results, without test
ing of any sort, and concluded the article.
Why, then, is Binford's identification of the fea
tures as smudge pits so compelling? Embedded
within the article are clues to Binford's actual sys tem of reasoning. At the start of the article Binford
discussed several different explanations for the
smudge pits. He noted that some archaeologists
(e.g., Newell and Krieger 1949:248-249) consid
ered them post molds "presumably because of their
small size" (Binford 1967:5-6). Other archaeolo
gists (e.g., Cole et al. 1951:156) argued that these
features were caches, "in spite of the fact that none
of the corncobs had kernels attached" (Binford
1967:5). Finally, Binford noted his own earlier
interpretation that the smoke from the smudge pits at one site "might have been employed in the con
trol of mosquitoes" (Binford 1967:4). However, Binford considered his own explanation "specula tion" based upon the "experience of the excavators"
(Binford 1967:4). Though Binford's analysis of the
competing explanations was limited, in each case
he found the explanation weak (mosquito control
and post molds) or contradicted by the existing evi
dence (caches). In contrast, Binford identified four
specific elements in the morphology of the features
(size, contents, treatment of contents, and final con
dition of the feature) that corresponded with the
ethnographic accounts of hide smoking (Binford
1967:8). Thus, that explanation that accounted for
the most, and the most diverse, evidence was con
sidered best. This, in turn, was considered prima
facia evidence for its truth.
Through the use of analogy, Binford con
structed an explanation for the function of a par ticular archaeological feature. In Wylie's terms, he
provided a principle of connection that linked the
disparate elements of his analogy. Despite his
claims to the contrary, the value of his explanation came from the empirical breadth that his explana tion subsumed. His hypothesis explained the fea tures better than any others he could think of. This,
by itself, was sufficient reason to accept the expla nation as likely to be true. Despite Binford's
rhetoric, his style of reasoning was essentially the same as Alfred Kidder's and, as we shall see, Ian
Hodder's.
Ian Hodder
In "Interpretive Archaeology and its Role," Ian
Hodder (1991) proposed an alternative system of
reasoning for archaeological research; one based
in the humanist and relativist perspective of post
processual archaeology. This system was
hermeneutics (an expanded discussion of
hermeneutics can be found in Hodder 1999; see also
Collingwood 1946; Ormiston and Schrift, eds.
1990; Shanks and Hodder 1995; Shanks and Tilley 1987a, 1987b; Thompson 1981). At the heart of the
hermeneutic process is the identification of differ
ent contexts and an attempt to bring understand
ings of these different contexts into a broader
coherent explanation. One context is that of the
archaeologist?the preconceptions, theories, and
social values that archaeologists bring to their
research. Another is the context of the people who
created the archaeological materials being investi
gated. Hodder argued that this latter context is dif
ferent from our own as it follows its own rules and
logic (see Hodder 1999:51-52). The hermeneutic
process consists of circling between these two con
texts, making each part fit into a coherent whole?
altering our views of our own context and the
archaeological context until the whole makes
coherent sense.
This movement back-and-forth between "our
context" and "their context" is not the only back
and-forth reasoning addressed by hermeneutics
(Hodder 1991:8). There are many other potential
oppositions that include: the past and the present,
specific instances and larger cultural patterns, our
culture and their culture, and others (see Hodder
1999:30-65; Shanks and Tilley 1987a). Metaphor
ically, hermeneutic research can be viewed as a cir
cle or, perhaps, a spiral (Hodder 1999), with each
movement back-and-forth altering the original
propositions that began each loop.
Among the strengths of the hermeneutic
Fogelin] INFERENCE TO THE BEST EXPLANATION 613
approach is its emphasis of the continuing, dynamic creation of explanations. In this sense, hermeneu
tics is a somewhat better model for the creative
process of explanation building than earlier, more
"scientific," epistemologies. These earlier models
also allowed for the continuing refinement of expla nations, but did not emphasize it with the same
zeal. Another strength of hermeneutics is its recog nition of the contingent nature of knowledge. While
Hodder does not resolve Cartesian skepticism?nor does he try?in a practical sense hermeneutics does
seem to more clearly identify and accommodate
issues of bias. What hermeneutic circles do not do,
however, is provide clear standards for what con
stitutes good explanations or standards for the rejec tion of weaker ones. Rather, hermeneutics
implicitly relies upon inference to the best expla nation to evaluate explanations, in much the same
way that Kidder and Binford did.
The reliance of hermeneutics on inference to the
best explanation is clearly illustrated within an
example of the hermeneutic process provided by Hodder (1991:7).
I recently came across a good example of the
everyday working of hermeneutic principles while listening to the radio in the United States.
I heard a phrase, or thought I did, "it was nec
essary to indoor suffering." ... I did not see
why it should be necessary to suffer indoors,
but then I know that North Americans ... are
willing to try anything. So initially I under
stood the term as it sounded to me and assumed
that the same word had the same meaning. I
then corroborated and adjusted this meaning
by placing it in the peculiar and particular rules
of North American culture.
Gradually, however, this process of internal
evaluation made less and less sense as I con
tinued to listen to the radio program.... Sen
tences such as "to indoor suffering I took a pain killer" made little sense. I could only make sense of these examples when I hit upon the
idea of another component of my understand
ing of the North American context: North Americans often pronounce words "wrongly."
... I searched and found "endure." Now every
thing made coherent sense and the whole had
been reestablished. The hermeneutic circle had
been closed [Hodder 1991:7].
While phrased in terms of the "part-whole rela
tionships" and "meaning," this example appears
fundamentally similar to the systems of reasoning discussed above. Hodder (1) encountered some
thing that did not make sense from his pre-existing
perspective (following Peirce's understanding of
inference to the best explanation), (2) proposed an
explanation, (3) compared it with the data, (4) found
the explanation unable to account for the full diver
sity of evidence, (5) developed a new explanation, and (6) accepted it as best due to its ability to
account for a broader range of empirical phenom ena. Further, this is not simply my interpretation of
this example. In the paragraph immediately fol
lowing this example Hodder states, "[w]e measure
our success in this enmeshing of theory and data
(our context and their context) in terms of how
much of the data is accounted for by our hypothe ses" (Hodder 1991:8). As with all the previous
examples, the ability of an explanation to account
for greater empirical breadth is taken as prima facia evidence for its truth.
Hodder's primary goal in writing the article
quoted above was to argue that postprocessual hermeneutics required some degree of "guarded
objectivity" (Hodder 1991:8). The value of
"guarded objectivity" is that "material culture as
excavated by the archaeologist is different from our assumptions because it is organized partly at
least according to other cultural rules" (Hodder 1991:12). Thus, at a basic level, Hodder rejects the relativism of earlier postprocessual archaeologists (including his own work). It is important not to
overplay this. Hodder continues to argue for the
importance of self-reflexive research and for the
recognition that, to some degree, archaeologists'
pre-existing beliefs will inform their interpretations of the past. The material remains, however, are not
amenable to just any interpretation. Some inter
pretations will be shown wrong through a failure to account for the diversity of evidence that is struc tured by people in the past. For Hodder, this would allow for feminist and ethnic minority voices to
challenge traditional archaeology while allowing for the rejection of bogus claims from the archae
ological fringe (Hodder 1991:9). I see no reason to quarrel with Hodder's claim
to an independent objective world beyond the
archaeologist. Like Hodder, I would not argue that this world can be objectively shown to exist, but it
614 AMERICAN ANTIQUITY [Vol. 72, No. 4, 2007
seems to be a useful starting point for further
research. What's more, I doubt any processual
archaeologist would have a quarrel either. A belief
in an objective world, no matter how guarded, is
fairly common. I also accept that archaeologists'
pre-existing beliefs will influence their interpreta tions. The important point for this discussion is the
reason why Hodder feels compelled to reassert the
need for guarded objectivity. He is trying to reduce
the inherent relativism of earlier postprocessual
approaches to the past.
The organized material remains have an inde
pendence that can confront our taken for grant
eds. The notion that the data are partly
objective is an old one in archaeology, and it
was the basis for processual and positivist
archaeology. But the trouble with positivist and processual archaeologists was that they did not incorporate hermeneutic and critical
insights [Hodder 1991:12].
By Hodder's own words, then, the differences
between postprocessual and processual archaeolo
gies are the use of hermeneutics and critical the
ory. But if hermeneutics relies heavily upon the
same epistemological system of evaluating expla nations, the only significant differences between
processual and postprocessual archaeologies are
the greater dynamism of hermeneutics and the use
of critical theory. These differences are far less pro nounced with processual-plus archaeology.
In the end, it is not Hodder's acceptance of
"guarded objectivity" or use of hermeneutic spi rals that is doing the work of rejecting inferior inter
pretations, though they are important. Rather, it is
the stated belief that the explanation that accounts
for the greatest breadth of material evidence is also
the one that is most likely to be true. It is not the
external existence of an objective world or
hermeneutics that allows for evaluation of expla
nations, only a straightforward standard of rea
soning common throughout archaeology for at least
a century. It is inference to the best explanation. In later works, Hodder greatly expanded his dis
cussion of the criteria used to judge explanations
(see Hodder 1999:30-65). In some ways Hodder's
criteria mirror those that I propose at the end of this
article. Given this, I will address this point when I
introduce my own criteria for evaluating explana
tions toward the end of this article.
Michelle Hegmon and Wenda R. Trevathan
To conclude this review of archaeological uses of
inference to the best explanation, I will examine a
recent article that falls into the processual-plus
approach of American archaeological research. As
the term "processual-plus" was coined by Michelle
Hegmon (2003)?and she self-identifies as a
practitioner?I will focus on an article she cowrote
with Wenda R. Trevathan (Hegmon and Trevathan
1996). In this short article, Hegmon and Trevathan
attempted to identify the gender of the people who
painted Mimbres black-on-white pottery in the
American Southwest during the Classic Mimbres
period (A.D. 1000-1150). Through ethnographic
analogy with later pueblo societies, some archae
ologists argued that women were more likely to
have been potters and pot-decorators (Moulard
1984; Shafer 1985), while other archaeologists sug
gested that men may have been the primary pot ters, or at least pot-decorators (Brody 1977; Jett and
Moyle 1986). Others argued that different stages of pottery production were performed by men and
women (Mills 1995; Wright 1991). Within this context of competing explanations
for ceramic production, Hegmon and Trevathan
examined the depictions of birth on three Mimbres
pots. In each they found that the depiction of birth
was radically different from actual birthing prac tices. First, the babies were facing the same direc
tion as the mothers, rather than backwards as is
typical. Second, the babies were depicted being born hands-first rather than headfirst.
Our analysis of a Mimbres birth scene suggests
to us that it was unusual, perhaps impossible,
and therefore probably painted by someone
not familiar with the details of birthing. Thus, we conclude that the scene probably was
painted by a man and that men may have been
the primary painters of Mimbres figurative
designs [Hegmon and Trevathan 1996:752].
Since no woman would depict birth as inaccu
rately as is found on Mimbres vessels, Hegmon and
Trevathan argued, it was more likely that men were
pot-decorators. This explanation was further sup
ported through ethnographic accounts from the
southwest stating that men rarely witnessed births.
As in the previous example, Hegmon and Trevathan
accept their explanation as true based solely upon its ability to explain the depictions of childbirth on
Fogelin] INFERENCE TO THE BEST EXPLANATION 615
Mimbres pottery better than any other explanations
they could think of. Hegmon and Trevathan may be wrong, but again that only underscores the
inductive nature of their arguments.
Summary
In all of the examples discussed above, hypothe ses or explanations were accepted or rejected based on the breadth and diversity of evidence that they accounted for. None of them could be called deduc
tions or statistical inductions. As for the use of
analogy by Binford, his acceptance of the expla nation that smudge pits were used in smoking hides still rested on inference to the best explanation.
These examples illustrate the ubiquity of infer ence to best explanation in archaeological reason
ing for at least a century. What remains, however, is a discussion of how the recognition that infer ence to the best explanation is typical of archaeo
logical reasoning can improve archaeological research. If archaeologists are already effectively
using inference to the best explanation, why worry about it? To answer this question I must first
address another?what does an explanation explain and how does it explain it? This turns out to be a very difficult question, with several differ ent approaches presented in the philosophical lit erature. Yet, if we are to determine what the best
explanation is of any archaeological phenomenon, we must have a clear understanding of what an
explanation is in the first place.
Explanation
There are many different ways that philosophers have come to understand explanation. Far more,
in fact, than can possibly be discussed here.12 All seem to have value in certain cases. Even the
deductive-nomological system of Hempel (1965, 1966) seems to work in the natural sciences and, to some extent, in those areas of archaeology most
closely linked with the natural sciences. In archae
ology, explanation has been typically viewed in terms of causation. An alternative way to under
stand explanation is in terms of contrasting statements?an explanation explains why some
thing occurred in terms of why another did not. As will be discussed below, I see contrastive expla nation as a more productive avenue for archaeo
logical reasoning.
Causal explanations
One way of understanding explanation is to con
ceive of it in terms of cause. An explanation of a
phenomenon identifies the cause of that phenom enon. Thus, if an archaeologist wants to explain
why there is a concentration of lithic debitage in one portion of a site, he or she might argue that it was created by a lithic workshop. This, of course, does not explain why there was a lithic workshop in the first place. This is the problem of infinite
regress. Every causal explanation seems to demand a further explanation ad infinitum. Each of these
earlier causes is a part of the causal history of a
particular phenomenon. Further, at some point the
why questions cannot be answered and the causal
history ends with "I don't know." More problem atically, it also becomes reasonable to argue that a cause of a high concentration of lithic debitage in one portion of an archaeological site is that some
fish crawled onto land 350 million years ago. This
is not what we are looking for in an archaeologi cal explanation. Several different approaches have been used to address the problem of infinite
regress.
The most straightforward approach to the prob lem of infinite regress is to focus solely on proxi
mate causes?the first, or first few, causes in the causal history of a phenomenon. The problem with this approach is that the next few steps of the causal
history might be very interesting, perhaps more
interesting than the proximate causes. Returning to
the lithic concentration example, stating that there is a lithic workshop has several implications on the forms of craft production practiced by the people
who lived in the site. It could suggest that one fam
ily produced all of the stone tools for people living at that particular site. Alternatively, it could sug gest that cooperative labor was employed by the
village within a communal workshop. Moving beyond proximate cause in this case could lead to
potentially interesting explanations. In practice it seems that archaeologists are not looking for prox imate causes but rather interesting and explanatory causes that are "proximatish."
Hempel (1965, 1966) had a different view of what makes a good scientific explanation. Rather than identifying proximate causes, Hempel sought to relate the particulars of a phenomena to an exist
ing set of universal or probabilistic laws (see Hempel 1966:chapter5).
616 AMERICAN ANTIQUITY [Vol. 72, No. 4, 2007
[L]aws play an essential role in deductive
nomological explanations. They provide the
link by reason of which particular circum
stances can serve to explain the occurrence of
a given event. . . . The laws required for
deductive-nomological explanations share a
basic characteristic: they are, as we shall say,
statements of universal form [Hempel 1966:54].
For example, an explanation for why a particu
lar object falls, and why it falls at a specific rate, would make reference to the laws of gravity
(Hempel 1966:54). The laws of gravity, then, serve
to explain the particulars of falling bodies.
The deductive-nomological approach to expla nation has been productive and useful in many nat
ural sciences and those areas of archaeology most
closely linked to them. However, as discussed ear
lier, universal laws of human behavior have not
been forthcoming in archaeology. In the absence
of widely accepted universal laws to reference, the
deductive-nomological approach fails to provide a
suitable foundation for many, if not most, archae
ological explanations.
Channeling Ernst Mayr (1982) and Aristotle, Kent Flannery (1986) proposed an alternative way of understanding explanation in archaeology. Rather than searching out a single proximate cause
or a set of universal laws to explain a phenomena,
Flannery argued that explanations in the historical
sciences need to address four different types of
causes, all first defined by Aristotle. These are: the
material cause, the efficient cause, the formal cause,
and the final cause. Each of these four types of
causes have different emphases. For example, "The
material cause is that out of which something is
made," while "the final cause is that for the sake of which something is made" (Flannery 1986:517,
emphasis in original).
Flannery's discussion of causation deserves
more time than is available here. In my view, while
Aristotle's types of causation are conceptually use
ful for understanding the variety of causal expla
nations, they do not provide a way to determine if
any one causal explanation is good, bad, or indif
ferent. The types do not lead to a method for con
structing or evaluating explanations about the past.
Rather, these types only provide a system that more
specifically identifies the ways that different "prox imatish" causes can be considered interesting. As
for a method to determine which explanations are
good, here Flannery relies on Mayr, who in turn
seems to rely on inference to the best explanation.
According to Mayr (1982:26 as cited by Flannery
1986:513), biologists accept as true "that which is
consistent with more, or more compelling, facts
than competing hypotheses." There is another problem with causal explana
tions. Many explanations do not identify causes,
they focus on meaning. For example, I might be
reading a book and come across a word with which
I am not familiar. I might come up with several dif
ferent ideas of what the word might mean based on
similarities to words I know or the context of the
word within the text. I would evaluate these poten tial meanings and, with luck, come up with an
explanation of what the word, as used in the par ticular text, means. Following the common under
standing of cause, it would not appear that this
could be described as a causal explanation. The
processual obsession with causal explanations was, in my view, correctly critiqued by postprocessual
archaeologists. They stress the value of interpre tive archaeology as corrective (Hodder 1991; Shanks and Hodder 1995). As I will discuss below, I see interpretation and explanation as fundamen
tally similar enterprises. Within the understanding of explanation presented below, explanations of
both cause and meaning are possible.
Contrastive Explanations
There is another way to understand explanation,
one that is favored here. Explanations can be
understood in terms of contrastive pairings (Lip ton 1991:chapter 5). Asking why there is a con
centration of lithic debitage in one portion of a
site requires additional statements before it can be
explained. It requires a. foil. A foil is a counter
point to the explanation being searched for. The
lithic workshop explanation will need to address
why there is a concentration of lithic debitage in
one particular area of the site rather than an even
scatter of debitage across the entire site. With the
addition of the foil the problem of infinite regress is limited. It no longer makes any sense to explain this through calls to 350-million-year-old fish.
The fish explanation does not account for why lithic debitage would be concentrated rather than
diffuse. In contrast, a lithic workshop would likely cause a concentrated scatter of lithic debitage and
Fogelin] INFERENCE TO THE BEST EXPLANATION 617
not cause an even scatter of debitage across the
entire site. When viewed in terms of the con
trastive pairing, a lithic workshop explains the
observed pattern of lithic distribution and simul
taneously refutes the foil. Admittedly, there are
also numerous other explanations that could
account for a concentration of lithic debitage within a single portion of a site (e.g., erosion pat
terns). This illustrates an important limitation of
contrastive explanation: it only evaluates the
stated explanations. It does not remove the poten
tial for other, unknown explanations of the same
phenomenon. Once more, however, this is typical of all inductive arguments.
Foils serve to focus explanations. While there are many potential explanations, not all of them will serve to explain why one specific thing occurred
and another specific thing did not.13 Foils have
another valuable feature, they can be changed. Sup
pose I rephrase the initial question to, "why is there
a concentration of lithics in one particular area of
the site rather than a concentration in a different area of the siteT Here the previous workshop
explanation does not explain why that workshop was placed in one part of the site and not another.
We might argue, employing some other evidence
in the process, that the workshop was placed within a family compound because it was a family controlled workshop. The explanation has changed as a result of the change in foils. There is one impor tant point here. The explanation from the previous foil is still there; this concentration is still a con
sidered a lithic workshop. Explanations using dif ferent foils can supplement, even strengthen, one
another. As will be discussed below, explanations that are consistent with multiple foils are, in gen eral, better than those that only address one.
As presented by Lipton (1991:chapter 5), con
trastive explanations are a form of causal explana
tion. I agree that contrastive explanations are often
also causal explanations. I do not agree, however,
that contrastive explanations are always causal
explanations. Contrastive explanations and the use
of foils are equally valuable in examinations of
meaning. In the previous example of the meaning of an unknown word, it would make sense to seek to explain that the word means x rather than y. Thus,
the use of contrastive foils is not limited to causal
explanations, but applicable to interpretations of
meaning as well.
Most archaeological explanations employ foils
implicitly, but sometimes explicitly as well.
Returning to the archaeological examples dis
cussed above, Kidder contrasted his "hostile
nomad" explanation with a desiccation explana tion of pueblo aggregation. Binford contrasted his
interpretation of smudge pits for hide smoking with explanations that labeled these features post molds, caches, or smudge pits used for the control
of mosquitoes. Hodder contrasted his interpreta tion of the word "endure" with his earlier under
standing of "indoor." Finally, Hegmon and
Trevathan contrasted their explanation that men
painted the figurative designs on Mimbres pottery with explanations that claimed women did. In each
case, the archaeologists used a foil to strengthen and direct their explanations.
At first glance, it might seem that I advocate
contrasting any two explanations for a specific
phenomenon to determine which is best. In some
cases, in fact, this is exactly what I advocate.
However, there is an important caveat. The fact
and the foil must be mutually exclusive. For
example, it is not possible to have a lithic scatter
that is both concentrated and diffuse. However, the question, "why is there a concentration of lithic debitage in one particular area of the site
rather than a high frequency of scrapers within
the lithic assemblage?" will not produce a con
trastive explanation. Typically, explanations must
address the same foil in order to determine which
is better. For example, inference to the best expla nation could determine whether erosion or the
presence of a lithic workshop is a better expla nation for why a lithic scatter is concentrated rather than diffuse.
I am not proposing that archaeologists adopt foils in their archaeological explanations. Rather, I am suggesting that it is already the implicit prac tice of most archaeologists. By making our foils
explicit, we can greatly improve our explanations and clarify the muddied debates that seem to per vade our discipline. Many of the explanations that are alleged to contradict each other are simply
addressing different foils. The use of different foils also allows for specific archaeological phe nomena to be explained in several different ways,
providing a justification for postprocessual claims
concerning the multivocality of archaeological data.
618 AMERICAN ANTIQUITY [Vol. 72, No. 4, 2007
Seven Traits of Highly Successful Explanations
So far, this article has focused on presenting what
inference to the best explanation is and discussing its strengths and weaknesses in terms of good
archaeological research. The question remains,
however, if archaeologists are already employing inference to the best explanation, why should they
spend time reflecting on it? The remainder of this
article seeks to answer this question. I conclude the
article with a discussion of the role of hypothesis
testing in archaeology in the light of inference to
the best explanation. But first I present a set of cri
teria that makes explicit the implicit criteria archae
ologists typically employ when evaluating
explanations.
What, then, makes an explanation a good expla
nation, and what makes one more compelling than
another? Philosophers have examined these ques tions for a long time, developing sophisticated
understandings of good explanations. Quine and
Ullian (1978:43) refer to "five virtues which count
toward the plausibility [of a hypothesis]." These
virtues are: generality, modesty, refutability, con
servatism, and simplicity. To Quine and Ullian's
virtues, I add two more, that good explanations should be empirically broad and should address
multiple foils.
In some ways, these criteria are similar to those
presented by Hodder within a discussion of evalu
ating the fit of an interpretation (1999:59-62). His
criteria include: internal and external coherence,
correspondence, fruitfulness, and simplicity. There
is overlap between my criteria and Hodder's, but
there are also significant differences in emphasis. Most importantly, I assert that these criteria should
be used?and often are used?by both processual
and postprocessual archaeologists. Hodder limits
some, but not all, of his criteria to postprocessual
archaeologists alone.
Before proceeding, I must note a critical limi
tation of these standards. These characteristics of
good explanations are taken from Western philoso
phers and are clearly derived from a Western intel
lectual tradition. As with any system of explanation, the political, social, historical, and other factors
affect what explanations individual archaeologists determine are best. Further, based upon the con
structivist arguments that underlay postprocessu
alism, there is no epistemologically consistent sys tem to overcome these biases and achieve objec tive truth. This does not mean, however, that these
biases cannot be addressed in several practical ways.
Just as I have argued that archaeologists should
not judge the success of an explanation by its abil
ity to establish irrefutable truths, the standards for
judging bias should not be absolute either. In this
light, archaeologists have long been using a vari
ety of practical methods to address bias. Some of
these methods deal with specific issues (e.g., the
tendency to round numbers to 5 or 0), while other
methods have far broader significance (e.g., the
method of multiple working hypotheses [Cham berlain 1965]). Hermeneutics, among its other uses, can also serve as a practical method to address bias.
These methods for the reduction of bias can and do
fit within the perspective of inference to the best
explanation. Ideally, the following list of traits that
characterize compelling explanations would
include methods for the reduction of bias, but there
is simply no way to do justice to the topic without
doubling the length of this already long article.
While valuable, a discussion of bias must be post
poned to another day. The following standards that characterize com
pelling explanations are not absolute or distinct.
They blend at the edges and, at times, conflict with
each other. These are guides to good reasoning, not
absolute prescriptions. The evaluation of any expla
nation has an impressionistic element that can never
be fully removed. Any specific explanation may be
strong in some elements and weak in others. Since
even the best hypothesis might not be good enough to warrant serious consideration, the following stan
dards can also be used to determine if the best
explanation is also a good explanation. Finally, I
am not arguing that these standards are complete.
Just as I have added a new standard to Quine and
Ullian's list, I hope that other archaeologists will
add to those I present here.
Empirical Breadth
I begin with a virtue not explicitly mentioned by
Quine and Ullian?though clearly implied through out their discussion?a good explanation should
address a wide variety of observations or evidence.
A good explanation should explain many empiri cal observations and not be contradicted by others.
Fogelin] INFERENCE TO THE BEST EXPLANATION 619
Empirical breadth can be understood in two ways. In the first, breadth is measured by the ability of an
explanation to account for large numbers of highly similar phenomena. This understanding of breadth
is used in evaluating statistical inductions and infer
ences to the best explanation. Alternatively, breadth
can be measured by the diversity of phenomena
explained. In the terms more familiar to archaeol
ogists, the best explanation should address multi
ple lines of evidence. Only inference to the best
explanation places value on this type of breadth.
The value of multiple lines of evidence in terms
of inference to the best explanation is fairly straight forward. In theory, there are infinite numbers of
explanations for any quantity of diverse observa
tions. In practice, however, explanations that employ
multiple lines of evidence are hard to come by, and
stronger for it. As the quantity of evidence subsumed
within the explanation increases, the number of
potential explanations for that evidence decreases.
The relative strength of any one explanation, there
fore, is believed to increase as the quantity and vari
ety of the evidence it encompasses increases.
The value placed on diverse evidence in the eval
uation of inferences to the best explanation stands
in contrast to statistical induction. As discussed
earlier, statistical inductions are weakened by the
addition of premises. This is due to the problem of
multiplying error. Inference to the best explanation, when evaluated in terms of the diversity of its
empirical breadth, provides justification for the
importance archaeologists already place on multi
ple lines of evidence in archaeological reasoning.
Generality
A good explanation should also be applicable to a
wide variety of phenomena. This is similar to the idea of empirical breadth, but there is a difference in emphasis. Here the measure is not that one spe
cific set of empirical observations employs a wide
variety of evidence, but rather that the same kind of explanation can be employed in a wide variety of cases. The strength of the concept of biological evolution is not simply judged on its ability to
explain the diversity of finches on the Galapagos Islands, but its broad application to biological phe nomena in general. By these standards biological evolution is a very general explanation. Marxism,
in its various guises, is a general explanation in the social sciences.
Modesty
With all this talk of generality and breadth, the
value of modesty might seem an odd addition to
this list. It is important, however, not to overreach.
I am sure we can all think of examples of someone
who has a pretty good explanation for some phe nomena, but applies it to everything. This standard
is a check on the previous standards. Don't try to
explain too much.
Refutability
For good reason, people distrust explanations that cannot be shown to be wrong. Irrefutable explana
tions come in two general types. In the first, the
explanation itself may defy falsification. Some cre
ationists, for example, have argued that God has
placed fossils in the ground as a test of scientists'
faith. Mere humans will always lose a battle of wits
with an omnipotent being. In the second case, an
explanation might be refutable but the evidence to
refute is, in a practical sense, impossible to acquire. For example, falsification might require an exper iment that would take 10,000 years to complete.
Here the explanation is technically falsifiable but
practically unfalsifiable. In the first case, the inabil
ity of the explanation to be refuted would be suffi
cient grounds for outright rejection, in the latter it would only weigh heavily against the explanation.
Conservatism
Good explanations should also be conservative.
They should not throw out well-established expla nations or principles on a whim. At times, of course,
new explanations will replace well-established ones. However, the standards for acceptance of
these explanations will be higher than for those that are conservative.
Simplicity
This standard is similar to conservatism. Simplic ity has long been recognized as a virtue in expla
nation (e.g., Occam's Razor). In general, a simple
explanation for a particular phenomenon is
accepted over a complex one, all other things being equal. Explanations should not create laws, uni
versal principles, or similar concepts that are not
needed, even where they do not conflict with well established principles. At times, some explanations turn out to be very complex. This is okay. The stan dard of simplicity does not argue that every expla
620 AMERICAN ANTIQUITY [Vol. 72, No. 4,2007
nation must be simple, only that archaeologists should not complicate their explanations any more
than is necessary.
Multiplicity of foils
To Quine and Ullian's set of virtues I add another, derived from Lipton's (1991:chapter 5) discussion
of foils. The more foils accounted for by an expla nation, the better the explanation. To my mind, this
standard for assessing an explanation is almost as
important as an evaluation of its empirical breadth.
When discussing foils above, I presented what
might be termed specific foils. For example, why is lithic debitage concentrated on one part of a spe cific archaeological site rather than another part of
that site? Here it might be best to think of foils in
a more general sense. Why do some phenomena occur at one place rather than another? Why do
some phenomena occur at one time rather than
another? Why do some phenomena take a certain
form rather than another? Through simple word
substitution, a whole variety of different foils can
be created, and then applied to specific cases. As
foils are explained, there will a corresponding increase in the strength of the argument. Phrased
more simply, an explanation that can account for
both where and when a particular event occurred is
usually better than an explanation that only accounts for when a particular event occurred.
Summary
On balance, those explanations that are empirically broad, general, modest, conservative, simple,
refutable, and that address many foils are more
compelling than ones that lack these traits. Based
on past experience with other explanations, it is
inferred that more compelling explanations are also
more likely to be true. These standards for evalu
ating the strength of an explanation are exception
ally good at comparing the relative merits of
different explanations of the same phenomena. It
allows an archaeologist to say that one explanation is better than another. However, when engaging in
inference to the best explanation, it must be remem
bered that the best of several explanations could still
be awful.
The same standards used to determine if an
explanation is best can also be used to determine
if an explanation is sufficiently good as to merit seri
ous consideration. When an explanation is partic
ularly good or bad, the standards provide strong
guidance. However, there will always be those
explanations that lie in the middle. While agreeing on all the evidentiary and argumentative particu lars of a middling explanation, two archaeologists
might differ on whether it is good or bad. We should
not trouble ourselves too much with this. In either
case, it would make sense either to improve the
explanation or to find another that is better. We
should also recognize that the standards listed
above often conflict with one another (e.g., mod
esty and generality). The judgments we make on
explanations are impressionistic, based upon our
past experiences with other explanations.
Multiple Explanations and Testing
As noted by Harman (1965, 1968) and Lipton (1991), many inferences to the best explanation are
sufficiently strong as to be effectively unchal
lengeable. They are accepted as true without any further testing or examination. It seems likely that
Binford never tested his assertion that smudge pits were used for hide smoking because he believed
his initial explanation was already sufficiently
strong. Even the most seemingly certain explana
tions could potentially be wrong, but testing and
further examination can quickly reach a point of
diminishing returns. Often, however, an explana tion is not sufficiently strong and requires further
investigations before it can be accepted. In these
cases rigorous testing is a reasonable and effective
system to evaluate an explanation. When explana
tions are of the appropriate form to construct
hypotheses and valid deductions, the hypothetico deductive method is a powerful approach for test
ing explanations. In other cases, testing can employ inference to the best explanation.
In contrast to deductive tests where hypotheses can only be rejected or confirmed, when using infer
ence to the best explanation to perform tests expla nations are made more or less compelling. With a
favorable test result the explanation is made more
compelling by increasing its empirical breadth.
With an unfavorable test, the empirical breadth of
the explanation is reduced through the identifica
tion of negative result. A larger proportion of the
observed data now contradicts the explanation than
before the test was performed.14 Another possibil
ity, one that is surprisingly common, is that the
Fogelin] INFERENCE TO THE BEST EXPLANATION 621
archaeological remains uncovered are unrelated to
the original research questions. In this case, no
change in the strength of the explanation occurs
directly. However, the new information might sug
gest a new explanation, one that accounts for both
the previous evidence and the new material in a par
ticularly robust way. In this case, the new expla nation would be accepted since it would be more
compelling than the previous one. It is in this light that Binford's (1967) "deductively drawn"
hypotheses concerning smudge pits can be under
stood. Binford's hypotheses, if tested and con
firmed, could have served to further expand the
empirical breadth of his explanation even though his hypotheses were not deductively drawn. This
in turn would have made his hide smoking expla nation even more compelling.
Inference to the best explanation accounts for
several elements of testing that are not supported within the hypothetico-deductive method. First, it
allows for testing of explanations that do not lend
themselves to deductively drawn hypotheses. Sec
ond, while testing of this sort does not clearly con
firm or negate a hypothesis, it does expand or reduce
the empirical breadth of an explanation. This in turn
makes an explanation more or less compelling.
Third, testing through inference to the best expla nation allows for the investigation of unique archae
ological phenomena. Tests can be designed to
expand the diversity of empirical evidence con
cerning rare or unique archaeological phenomenon.
For example, an archaeologist could test an expla nation against previously unexamined aspects of
the Pyramids of Giza. Fourth, this view of testing allows for the relative success of a test to be gauged.
In the hypothetico-deductive framework, hypothe ses are either confirmed or denied. In reality, archae
ologists have all seen test results that are more
equivocal. Finally, testing in this light resembles
what archaeologists actually do, whether proces
sual, postprocessual, or something in between.
When reading the philosophical literature on
inference to the best explanation, it sometimes feels as if philosophers assume that in most cases a sin
gle clear explanation will become evident?that the cream will inevitably rise to the top. In my own
experience I am not so sure. It seems that the hard cases are remarkably common. Many archaeolog
ical phenomena have multiple explanations that are
either of equal quality or oddly unrelated. In prac
tice, postprocessualists seem right when they sug
gest that multiple perspectives can be brought to
archaeological explanations. In terms of inference
to the best explanation, there are two ways in which
this can occur. In the first, two or more good expla nations of the same archaeological phenomena that
address the same foil are of similar quality. Dif
ferent archaeologists might lean toward one or
another, but neither of the potential explanations is
clearly the best. In the second case, good explana tions of the same archaeological phenomena address different foils. In this case there is no direct
link between the explanations. They are more like
ships passing in the night. For example, one expla nation might explain why a certain archaeological
phenomenon occurred at one time rather than
another. Another explanation might explain why the
same phenomenon occurred in one place rather
than another.
These two sources for multiple explanations
require different strategies to accommodate them.
Where two explanations have different foils, no
amount of testing will show which one is best. It
would be possible to rank the explanations in terms
of how well they satisfy explanatory standards, but
since they do not share the same foil, there is no
reason to reject the weaker of the two arguments as long as it is at least a good explanation and does
not substantially contradict the stronger.15 There are
two strategies to employ in this situation. First, be
happy that you have two good explanations and use
them for your research appropriately given the foil
you are investigating. It's often hard to find even
one good explanation?so count your blessings.
Second, think up a better inference to the best expla nation that accommodates the differing foils. This
may entail synthesizing the two explanations, or
replacing them with a wholly different, all
encompassing explanation.
When multiple explanations share the same foil,
testing is a very practical way to evaluate them. One
strategy would be to start testing each explanation
independently and seeing which one winds up with
the most empirical breadth. A better strategy, how
ever, would be a test that served to contrast the
explanations. The test should not only make one of the explanations more compelling, but also simul
taneously make the others less so.
Even with our best efforts, multiple explanations for the same archaeological questions will likely
622 AMERICAN ANTIQUITY [Vol. 72, No. 4,2007
persist in archaeology. In this sense, postprocessual
archaeologists are right. There are multiple expla nations of specific archaeological phenomena. Fur
ther, all of these different explanations have value to the extent that they are good explanations. One
of the primary criticisms of postprocessual archae
ology is that it does not have a mechanism to refute
terrible explanations of past events (Earle and Preu
cel 1987). Inference to the best explanation, par
ticularly when paired with contrastive explanations,
provides a mechanism for dealing with this prob lem. Bad explanations can be rejected by reference
to the standards of empirical breadth, generality,
modesty, etc. Good explanations of equal worth
when addressing the same foils, or even good expla nations of different worth when addressing sepa rate foils, can be accounted for.
Conclusion
Both hermeneutics and the hypothetico-deductive method are good approximations of inference to the
best explanation and have value in archaeological research?but both also employ philosophical
gymnastics that conceal the similarities between
them. These similarities in reasoning serve to
explain, in part, one of the issues that began this
paper: how do processual and postprocessual
archaeologists productively borrow data and ideas from each other despite the differences between
them? By sharing a common form of reasoning, and
common methods for the evaluation of competing
explanations, processual and postprocessual
approaches are not as different from each other as
either group typically assumes.
This article is not a rallying cry for the status
quo. Accepting that inference to the best explana tion underlies a great deal of archaeological rea
soning demands modifications to the practice of, and discourse about, archaeological research. Dis
cussions of the relative worth of different explana tions should more explicitly employ the standards
that make an argument compelling (empirical breadth, generality, modesty, conservatism, sim
plicity, refutability, and addressing many foils). If
testing an explanation, archaeologists must be clear
if they are using deductive tests or inductive tests
based on inferences to the best explanation. In the
former, the results can only negate or, in some
philosophical formulations, confirm hypotheses.
More commonly, archaeological testing will only make explanations more or less compelling.
Finally, by employing inference to the best expla nation, archaeologists can explore unique or rare
phenomena that defy investigation through deduc tion or statistical induction.
Throughout this article I have relied on a fairly
simple approach. I have focused on what archaeol
ogists do rather than on what they say they do.16 When viewed in this light, archaeologists have, for a long time, relied upon a style of reasoning well
suited to their goals: inference to the best explana tion. Despite several attempts to divert archaeolo
gists' epistemological interest elsewhere, inference
to the best explanation has persisted as a dominant
form of reasoning in archaeology for a very simple reason?it works. Despite the rapidly changing social theories employed in the development of
archaeological explanations, inference to the best
explanation has continued to be the primary means
for determining the value of individual explana tions. For this reason, I am not proposing that archae
ologists adopt inference to the best explanation. I
only suggest that archaeologists should accept as
worthwhile a style of reasoning they are already
using and do a better job of using it.
Acknowledgments. For over a decade now, my father (Robert
Fogelin, Professor Emeritus of Philosophy at Dartmouth
College) and I have been talking about philosophy in one
way or another. This article is my response to our discus
sions. Throughout the writing process he has continued to
help, pointing out philosophical blunders small and large.
Though I have relied on his assistance, there are several ways in which my father would disagree with what is presented
here. For his advice and help?in things far more important than philosophy?I dedicate this article to him. I thank Laura
Villamil for translating the abstract into Spanish. I also thank
the people who read and commented on the previous drafts
of this article, including: Andy Balkansky, Florence Fogelin, Severin Fowles, Jane Kelley, Scott Hutson, Alice Ritscherle,
Norm Yoffee, and two anonymous reviewers. The article is
far better for their insights. This article was written while
serving as the Visiting Scholar at the Center for
Archaeological Investigations at SIU Carbondale.
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Notes
1. Throughout this article I treat processual and post
processual archaeology as more theoretically unified than
they actually are or were. I recognize that there is a great deal
of diversity in the approaches of specific archaeologists asso
ciated with these different schools. The caricatures I employ are only intended to reduce hesitations and subclauses that
would only serve to distract from the main thrust of this arti
cle.
2. Throughout this article I cite Alison Wylie's Thinking
from Things (2002). This work contains her collected articles,
spanning the years since 1982.
3. Throughout this article I primarily cite and quote Carl
Hempel (1965, 1966) in my discussions of the hypothetico deductive method. However, Hempel's primary contribution was the characterization of scientific explanations as requir
ing universal or probabilistic laws (the deductive
nomological approach to explanation). For the most part,
Hempel's views on the hypothetico-deductive method follow
those of his contemporaries. 4. A similar definition can be found in The Oxford
Companion to Philosophy (Honderich, ed. 1995:181) which states that "[a deduction is] a species of argument or inference
where from a given set of premises the conclusion must fol
low."
5. Hempel (1966:11) notes the same difference between
inductive and deductive arguments: "The premises of an
inductive inference are often said to imply a conclusion only with more or less high probability, whereas the premises of a
deductive inference imply the conclusion with certainty." 6. Astronomical predictions, for example, are usually
inferential. Based upon previous observations of an asteroid's
location and some general laws of gravity, astronomers can
infer its future path. At first glance, this may seem a deduc
tion. However, the conclusion is not the necessary product of
its premises. For example, the asteroid may be hit by a comet or influenced by the gravity of an unknown object. In either
case, all of the premises of the induction would still be strong, but the comet would not follow the predicted path. Astronomical observations of this sort, then, are a form of
inductive reasoning.
7. In contrast to inductions, deductions are non
ampliative. The conclusion of a valid deduction contains no
more information than what is contained within its premises. 8. Harman (1965, 1968b) argues that even statistical
inductions rest upon a foundation of inference to the best
explanation. This is an exceedingly technical discussion that
need not be addressed here.
9. This argument concerning the limitations of statistical
inference follows closely that of Harman (1965). 10. Harman (1965:89) notes, "There is, of course, a prob
lem about how one is to judge that one hypothesis is suffi
ciently better than another hypothesis. Presumably such a
judgment will be based on consideration such as which
hypothesis is simpler, which is more plausible, which
explains more, which is less ad hoc, and so forth. I do not
wish to deny that there is a problem about explaining the
exact nature of these considerations; I will not, however, say
anything more about this problem." 11. Lipton (1991:chapter 7) contrasts the term "likeli
ness" with the term "loveliness." I find "lovely" to be prob lematic as a general term for describing the strength of an
explanation. For this reason, I use the term "compelling" instead. Other than this shift in terms, my argument follows
closely that of Lipton. 12. See, for example, John Stuart Mill's (1904) methods
for the identification of causes or Philip Kitcher's (1981)
analysis of explanation as a demonstration of unity, among
many others.
13. In a recent discussion of analogy in the study of
ancient states, Yoffee (2005:194) notes, "The search for
appropriate comparisons among the earliest states is a rela
tively new enterprise in social evolutionary theory, and its
important that the project's goals include not only explana tions of why things happened as they did, but also why they didn't happen some other way." While phrased in terms of
analogical arguments, Yoffee's suggestion fits neatly with the
concepts of foils and contrastive explanations presented here.
14. The same logic explains why particularly strong
explanations do not seem to require further testing and why, at a certain point, progressive loops in hermeneutic circles
become less productive. Where an explanation encompasses a particularly large amount of empirical evidence, contradic
tory evidence gained from testing will not affect the propor tion of supporting evidence for an explanation to any
significant degree. 15. It is likely that if two explanations contradict each
other they share at least one foil.
16. Hodder (1999:30-65) also claims to examine what
archaeologists do rather than what they say they do. I would
argue, however, that Hodder compares what postprocessual
archaeologists do with what processual archaeologists say
they do. As exemplified by Binford's (1967) "Smudge Pits," the actual reasoning practices of processual and postproces sual archaeologists are remarkably similar.
Received May 18, 2006; Revised October 5, 2006;
Accepted February 14, 2007.