Limitations on an Inclusive Definition of Ecosystem-Human Health

Ethics and the Environment

, 5(2):153–161 Copyright © 2000 Elsevier Science Inc.ISSN: 1085-6633 All rights of reproduction in any form reserved.

153

Limitations on an Inclusive Definition of Ecosystem-Human Health

David Castle

INTRODUCTION

The ecology movement has been effective in focusing our at-tention on humanity’s antipathy toward nature and the risks associated with that antip-athy. Evidence of the effects of human-caused environmental destruction performedin the march of progress has long been recognized, but it has been realized only re-cently that degraded environments can reciprocate and impose severe if not final lim-its on human pursuits. Ecologists and philosophers who have foreseen our environ-mental midnight have attempted to reformulate contemporary society so thathumanity and nature can work in concert, not in opposition. In this respect, the eco-logical movement has sponsored various forms of ecocentrism, all of which are dis-tinguished by their attempt to integrate the norms underlying ecosystem health andhuman health. Despite the fact that significant aspects of the ecocentrist platform havebeen called into question (Steverson 1994), the prospect of their integration still hasappeal. An integrated definition would imply that concern for human and natural wel-fare could be coextensive and that right action would simultaneously benefit humansand nature.

Ostensibly, an inclusive definition of ecosystem-human health must satisfy twobasic criteria. It must:

1. Articulate the relationship between human health and ecosystem health.2. Provide a set of norms that are consistent for human health and ecosystem

health.

I argue that an analysis of the basic principles underlying ecosystem health and hu-man health enable us to answer (1), but that it is not presently possible to answer (2)

Direct all correspondence to:

David Castle, Department of Philosophy, University of Guelph, Guelph,

ON N1G 2W1, Canada; Phone: (519) 824-4120; E-mail: [email protected]

154 ETHICS AND THE ENVIRONMENT Vol. 5, No. 2, 2000

in a way that would make for a truly inclusive definition. Here is a brief sketch of myargument:

The concept of ecosystem health is based on the science of ecology. Ecosystemhealth requires ecology to describe accurately the well-functioning of ecosystems;when it does, two basic kinds of norms are derived. On the one hand, we can describethe well-functioning of nature in itself. On the other, natural processes have conse-quences for our health—they are norms for us. Although norms of nature for us areultimately predicated on bionorms, not all bionorms entail consequences for us. Ac-cordingly, the relevant interactions required by the second criterion of an inclusivedefinition of ecosystem-human health are those that are identified by a limited set ofecosystem states that have consequences for us. In other words, ecosystem health

initself

, as described by the bionorms, is not wholly relevant to the inclusive definition.Turning to the second criterion, I argue that because important differences exist in

the way that ecosystem health and human health are characterized and measured, aconsistent set of health norms required by the inclusive definition cannot be acquired.Instead, the nature of the relationship between ecosystem and human health indicatesthat an inclusive definition of ecosystem-human health is a stepped process of under-standing the relevant interactions between humans and ecosystems, assessing the rele-vant bionorms, and determining their downstream consequences for us. I concludethat an inclusive definition of ecosystem-human health cannot contain a single set ofnorms but instead must rely on the analysis of the interactions between humans andecosystems.

THE CONCEPTUAL UNDERPINNINGS OF ECOSYSTEM HEALTH

The modern science of ecology bears little resemblance to itsintellectual progenitor — nineteenth-century natural history. Natural history has longbeen regarded as nonscientific because it is fundamentally descriptive and generallydoes not concern itself with causal explanations. Contemporary ecology, by contrast,provides causal explanations for the “processes influencing the distribution and abun-dance of organisms, the interactions among organisms, and the interactions betweenorganisms and the transformation and flux of energy and matter” (Collins 1986).Since the 1920s, ecology has increasingly used mathematical modeling techniquesand computer simulations (Kingsland 1995). The use of mathematical models is evi-dent in many of the most prominent theories in ecology, such as Lotka and Volterra’scompetition models (Volterra 1926) and MacArthur and Wilson’s theory of islandbiogeography (MacArthur and Wilson 1967), and is also true of much of the workfound in contemporary ecological journals, such as

Ecological Modelling

,

Oikos

, and

TREE.

Ecological models are mathematical idealizations intended to reveal putativecauses in nature. Mathematical models do this by describing ideal systems that coun-terfactually express how nature would behave if the causal relationships contained in

Ecosystem-Human Health

155

the model actually existed in nature (Castle 2000; Thompson 1989). Models permitsimple test implications for laboratory or field work to determine if there are in factsystems in nature whose causal relationships are mathematically isomorphic to the re-lations described in the model. In short, the science of ecology uses mathematicalmodels to generate explanations of natural phenomena.

The advent of sophisticated modeling techniques and the use of computer simula-tions has led to growing scientific consensus about the fundamental processes andstructures in the natural world. Ecological knowledge has increased to the extent thatwe know of a number of parameters that are consistent in all ecosystems. Measurablequalities of ecosystems, such as organization, function, and resilience are nowthought to be common to all ecosystems (Mageau, Costanza, and Ulanowitz 1995).Variances in the values of these parameters enable us to identify and categorize differ-ent ecosystem types (e.g., rocky inter-tidal, temperate rain forest, grassland). Theyalso permit comparisons between different ecosystems, or the same ecosystem at dif-ferent times, by noting changes in ecosystem behavior. Consequently, these measur-able parameters are indicators about what constitutes the normal functioning of differ-ent kinds of ecosystems, as well as the extent and kind of deviation away from anormally functioning state (Mageau, Costanza, and Ulanowitz 1995).

Ecology therefore provides descriptive indicators about what can be expected ofthe normal states of ecosystems. The concept of ecosystem health is grounded in theseindicators because it takes these descriptions of normal states as benchmarks for thewell-functioning of ecosystems. As Eugene Odum puts it, “when ecosystems are notaffected by strong external perturbations, such as storms or human disturbances, weobserve certain well-defined developmental trends . . . a disordering disturbance towhich a community is not well adapted arrests and, in many cases, reverses these au-togenic developments” (Odum 1985). In addition to being a descriptive claim, theidea of an ecosystem being well-functioning obviously introduces an evaluative com-ponent not found in the descriptions of nature generated by ecological models. Anecosystem is considered to be well-functioning if it has the measurable qualities asso-ciated with an system of its kind. So ecosystem health is essentially normative in itsassessment of these states because it takes the normal states of ecosystems to be thepreferable, healthy states. Ecosystem disturbances are unhealthy because they involvesome kind of privation of normal ecosystem qualities, a view endorsed the most well-developed account of ecosystem health, Ecosystem Distress Syndrome (EDS) (Rap-port 1995).

Since the principal focus of ecosystem health is on the internal states of ecosys-tems and not their ramifications for other ecosystems or for humans, health is a prop-erty of ecosystems in themselves. That is, ecosystem health is predicated on the ideathat ecosystems can be described as being well-functioning in themselves. Whether ornot this is an intelligible mix of description and evaluation, or if the concept of eco-system health invokes Moore’s naturalistic fallacy, is another argument for anotherday. These questions, although entirely relevant in the assessment of the concept ofecosystem health, are beyond the immediate challenge of providing an inclusive defi-


nition of ecosystem-human health. We may have to rely on a minimalist account ofthe descriptive and evaluative component of ecosystem health. Callicott (1995), forexample, has suggested that the idea of health is subjectively conferred on normal eco-systems—most likely by the ecologists studying the indicators of ecosystem health. Itis in fact preferable that this aspect of ecosystem health remains minimally defined,because it is therefore readily distinguishable from the metaphysical, intrinsic valueconception of health that characterizes ecocentrism (Warren and Cheney 1993).

Minimally, the concept of ecosystem health is both descriptive and normative.Because well-functioning of an ecosystem in itself is a normative interpretation of aset of natural states, the central claim underlying the concept of ecosystem health isthat biologically-based norms of nature in itself—bionorms for short—can be identi-fied by ecology. Bionorms, then, are normatively interpreted indicators of ecosystemhealth.

ECOSYSTEM HEALTH FOR US

Bionorms describe the well-functioning of an ecosystem initself according to benchmarks established by ecology. When bionorms are used todescribe the health of an ecosystem, they refer only to the internal states, the indica-tors, of that ecosystem. Strictly speaking, bionorms cannot be used to evaluate the ex-ternal influence an ecosystem may have. Specifically, bionorms are not themselvesindicators of an ecosystem’s influence on human health. Even when human health isaffected by an ecosystem, or by changes in an ecosystem, bionorms cannot be used toevaluate the effects on human health. Nor should they be expected to, since there arecases in which an ecosystem’s health has no impact on humans, yet human health cannevertheless be evaluated. So another approach must be taken to demonstrate and as-sess the consequences of the health of an ecosystem on humans.

It may seem odd in terms of the foregoing, but it is conceivable that the health ofan ecosystem could be evaluated on anthropocentric considerations alone. In effect,the claim is that

homo mensura

, and so no reference to bionorms or any other sourceof value, need be made. Instead, the impact of natural processes on humans would bedetermined by human ecology and medicine, and our evaluation of the effects on na-ture would reflect the values that we hold. On this ultra-anthropocentrism, nature’shealth would simply be coextensive with human health. This is not a satisfactory wayof assessing ecosystem health, however, for it ignores the progress ecology has madein finding ecosystem health indicators. Changes in ecosystems have ramifications forthe system itself, as described by bionorms, but they also have consequences for us, asour anthropocentric concerns indicate. Since neither bionorms nor anthropocentricconsiderations tell the whole story about ecosystem health, a complete conception ofecosystem health must incorporate both bionorms and human values. As we shall seein the next section, the causal relationships between them means that bionorms andhuman values may be conceptually distinct, but they are not separable in the conceptof ecosystem health.


157

THE RELATIONSHIP BETWEEN ECOSYSTEM HEALTH AND HUMAN HEALTH

The discussion so far has partially satisfied the first criterionof an inclusive definition of ecosystem-human health—that the definition is able toarticulate the relationship between the two—by confirming that this relationship doesindeed exist. But what kinds of interactions characterize this relationship?

For an inclusive definition, the most important relationships between ecosystemhealth and human health are causal relationships. Other types of relationships can bedescribed, such as temporal and spatial contiguity. Since these relationships do not in-volve interactions between humans and ecosystems, they are not of paramount impor-tance to an inclusive definition of ecosystem-human health. Instead, the focus must beon interactive relationships between human activities and ecosystem functions inwhich the state of one affects on the state of the other. For example, unhealthy ecosys-tem states can cause the disruption of vital ecosystem services to humans that are oth-erwise maintained by healthy ecosystems. Conversely, human activities affect ecosys-tem functions adversely if they are environmentally destructive, or positively if theyare environmentally restorative. In a third case, ecosystem states or human activitieshave no bearing on the other and are hence neutral interactions.

Notice, however, that whereas human activities and ecosystem states can havethese different kinds of interactions, the same is not true of ecosystem health and hu-man health. The health of ecosystems has significant consequences for human health,but the opposite is not true: human health, especially that of an individual human,does not have significant consequences for ecosystem health. This asymmetry will bediscussed below when the issue of the consistency of ecosystem and human healthnorms is considered. Its relevance here lies in when the interactions between humanand ecosystem health are examined with reference to actual cases, the causal chainruns from the health of ecosystems to the human health, and not vice versa.

Accordingly, Table 1 suggests the ways in which changes to an ecosystem’shealth can affect human health in some specific situations. Biodiversity is an impor-tant indicator of the well-functioning of an ecosystem. Since biodiversity is frequentlyheld to be a characteristic of healthy ecosystems, the examples are based on changes

Table 1. Interaction of Human Health and Ecosystem Health

Human Health

Ecosystem Health Positive value Negative value Neutral value

Positive value New species of drug plant evolves

New species of parasite evolves

New species evolves but no interaction with humans

Negative value Species of parasite goes extinct

Species of drug plant goes extinct

Species goes extinct but never interacted with humans

Neutral value Species of parasite goes extinct but new drug plant evolves

Species of drug plant goes extinct but new parasite evolves

New species evolves as other species goes extinct but neither interact with humans


to an ecosystem’s biodiversity. Accordingly, an ecosystem’s health can positively in-crease with the evolution of a new species, decrease with the extinction of a species,or remain neutral if there is a one-for-one replacement of one species by another.

Table 1 helps to makes explicit some important aspects of the human ecosystemhealth relation. First, notice that events that are positive for ecosystem health are notnecessarily positive for human health, and those that are negative for ecosystemhealth are not necessarily negative for human health. Asymmetries exist between thetwo. For example, changes to the biodiversity because of the evolution and extinctionof species do not necessarily lead to increases or decreases in human health. In thesame vein, there are cases in which changes in an ecosystem may be neutral with re-spect to that system’s biodiversity, but they are not neutral in their consequences forus. In a different scenario, there can be cases where changes to a system’s bionormshave no effect on human health whatsoever, so changes in biodiversity need not haveany effects on human health whatsoever.

These asymmetries and neutral effects indicate that the health of nature in itself isnot coextensive with human health. The two may be causally related, but the relation-ship must be assessed for each ecosystem state or changes to those states. In addition,the assessment of causal interaction between the two calls for proximate accounts ofdirect causal interaction. Knowledge of lengthy causal chains responsible for chang-ing ecosystem states may be essential to a complete understanding of bionorms, butthe focus of an inclusive definition is more narrowly concentrated intersection of eco-system and human health. It is therefore inappropriate to formulate an inclusive view,as Leopold and Naess have done, that depends on spurious claims that everything ismeaningfully interconnected. That kind of human and ecosystem integration does notexist (Steverson 1994), and the examples of asymmetry and neutral effects supportthis claim.

In summary, the first criterion of an inclusive definition can be satisfied, but withimportant qualifications. A definition of ecosystem-human health can be elaborated interms of the relationships between ecosystem and human health, but the relationshipbetween them is not coextensive. Instead, when we consider the bionorms used toevaluate the health of an ecosystem, it is apparent that not all states of health of an eco-system in itself are relevant for us. Therefore, out of the set of total possible states anecosystem may be in, only a limited set of those states are considerable under an in-clusive definition. What separates those states for consideration is that they are haveproximate causal impact on human health.

CONSISTENCY OF NORMS BETWEEN ECOSYSTEM HEALTH AND HUMAN HEALTH

An inclusive definition of ecosystem-human health cannotcontain a set of norms

common

to both because, as we have seen, the health of an eco-system in itself, as determined by bionorms, must be considered independently of theconsequences that system has for us. The second criterion of an inclusive ecosystem-


159

human health concept, however, requires that a

consistent

set of norms apply to eco-system health and human health. The reason for this criterion is that a consistent set ofnorms would entail that concern for human and natural welfare could be coextensive,and that right action with respect to one would either at least be neutral, or better, ben-eficial for humans and nature. In essence, the consistency criterion is intended to mit-igate against actions that promote the welfare of nature at the expense of human wel-fare, and vice versa. But is consistency attainable? In what follows, I shall providetwo sketches for why the answer is no.

First, there are fundamental differences in the concepts of health operating in eco-system health and human health. Human health is conventionally understood in termsof medical categories that describe a range of conditions under which an individualhuman can be considered to be well-functioning. In this respect, medically definedhealth is analogous to ecosystem health—a positively described set of conditions isinterpreted normatively in each case. This analogy is frequently (but falsely) conjec-tured to be the basis of the concept of ecosystem health, but at least one attempt hasbeen made to demonstrate that health can be interpreted to make the analogy work(McMichael 1995). The analogy is misleading, however, because human health andecosystem health are disanalogous in important ways. On the one hand, the health of ahuman is defined and evaluated in terms of the properties exhibited by an individual.The health of ecosystems, on the other hand, is not determined by the composition ofan individual, but in terms of the relations that persist between the parts of the ecosys-tem (Costanza 1992; Mageau, Costanza, and Ulanowitz 1995).

A second distinguishing feature is that the practice of human medicine generallytakes a “single cause” approach to diagnosing the illness of an individual, whereas thediagnosis of ecosystem distress requires the analysis of multiple causes between anumber of related parameters (Ehrenfeld 1995). Causes of ecosystem disturbancescan sometimes be singular if they are attributable to human intervention or some envi-ronmental factor, such as the explosion of Krakatoa. The ensuing changes to ecosys-tem health, however, do not have single causes, a fact that makes clinical diagnoses ofecosystem health more difficult and diffuse than their human counterparts.

The second problem with establishing a consistent set of norms reintroduces theissue of ecosystem health raised in the consideration of the first criterion for the inclu-sive definition. Ecosystem health, as defined by bionorms, can have clear conse-quences for human health in cases where there is a change in the bionorms that lead todifferent consequences for us. The classic example is the deterioration of an ecosys-tem leading to a reduction in ecosystem services for humans. The reverse situationdoes not exist. Changes to the health of a single or group of humans does not lead tocorresponding changes in ecosystem health. For example, there is no environmentalimpact from the reduction of cardiac risk factors through exercise or diet change. Ingeneral, human health, like ecosystem health, is something that is descriptive andevaluative in itself, but human health does not have reciprocal consequences for eco-system health. Asymmetry exists between the consequences arising from health ofecosystems on humans and the consequences arising from the health of humans on


ecosystems. This asymmetry arises because the same concept of health cannot describeecosystem and human health, as discussed above. Consequently, the norms of ecosys-tem health are not the same for human health. To put the point somewhat differently,changes in ecosystem health can be sufficient to cause changes in human health, butnot all changes in ecosystem health necessarily cause changes in human health. Be-cause changes in human health are neither necessary nor sufficient to induce changein ecosystem health, the norms used to evaluate one cannot be wholly consistent withthe norms used in the other. Consequently, there is no consistent set of norms for eco-system and human health, so the second criterion is not realizable.

CONCLUSION

The relationship between ecosystem health and human healthis limited to a set of causally proximate interactions that leaves many aspects of hu-man health and ecosystem health unrelated. That they can be unrelated underminesthe idea that a consistent set of norms can be developed and used in the evaluation ofecosystem and human health. Consequently, an inclusive definition of ecosystem-human health is not fully realizable.

Ecocentric and anthropocentric approaches to environmental ethics are assimila-tive in the sense that each must argue that its set of values can account for both humanand natural concerns. In the case of ecocentrism, for example, the assimilation of hu-man interests into the inherent value of nature is defended on such ecological groundsas community membership or the “interconnectedness of all things.” If what has beensaid here about the viability of an inclusive definition is correct, then assimilation ismore an act of smuggling than it is an act of integration. The desire to integrate theseemingly disparate realms of human and ecosystem health can run roughshod overthe nuances of the relationships between the two that I have described above. The re-sult is inconsistent with ecology’s drive toward greater, more detailed knowledge ofnature; it is also inconsistent with the differences that we know exist between humanand ecosystem health. In place of this view, I have suggested that an inclusive defini-tion of ecosystem-human health must see the relationship between human and ecosys-tem for what it is: a nonreductive set of causal interactions with normative implica-tions on both sides. The integrity of this relationship is central to an inclusivedefinition of ecosystem-human health, and it is foundational to any clinical assess-ment of either ecosystem or human health.

REFERENCES

Callicott, J.B. 1995. “A Review of Some Problems with the Concept of EcosystemHealth.”

Ecosys-tem Health

1: 101–112.Castle, D. 2000. “A Semantic Conception Ecological Theory.”

Dialectica

54: 289–304.Collins, J. 1986. “Evolutionary Ecology and the Use of Natural Selection in Ecological Theory.”

Journal of the History of Biology

19: 257–288.


161

Costanza, R. 1992. “Toward an Operational Definition of Health.” In

Ecosystem Health—NewGoals for Environmental Management

(pp. 239–256), edited by R. Costanza, B. Norton, andB. Haskell. Washington, DC: Island Press.

Ehrenfeld, D. 1995. “The Marriage of Ecology and Medicine: Are They Compatible?”

EcosystemHealth

1: 15–21.Kingsland, S. 1995.

Modelling Nature: Episodes in the History of Population Ecology

(2nd ed.).Chicago, IL: Chicago University Press.

MacArthur, R., and E.O. Wilson. 1967.

The Theory of Island Biogeography.

Princeton, NJ: Prince-ton University Press.

Mageau, M.T., R. Costanza, and R.E. Ulanowitz. 1995. “The Development and Initial Testing of aQuantitative Assessment of Ecosystem Health.”

Ecosystem Health

1: 201–213.McMichael, A.J. 1995. “The Health of Persons, Populations, and Planets: Epidemiology Comes Full

Circle.”

Epidemiology and Society: A Forum on Epidemiology and Global Health

6: 633–36.Odum, E. 1985. “Trends Expected in Distressed Ecosystems.”

Bioscience

35: 419–23.Rapport, D. 1995. “Ecosystem health: An emerging integrative science” In

Evaluating and Monitor-ing the Health of Large Scale Ecosystems. Heidelberg: Springer-Verlag

, edited by D.J. Rap-port, C. Gaudet, and P. Calow. 10–11.

Steverson, B. 1994. “Ecocentrism and Ecological Modelling.”

Environmental Ethics

16: 71–88.Thompson, P. 1989.

The Structure of Biological Theories.

Albany, NY: State Universities of NewYork Press.

Volterra, V. 1926. “Fluctuations in the Abundance of a Species Considered Mathematically.”

Na-ture

118: 558–60.Warren, K.J., and J. Cheney. 1993. “Ecosystem Ecology and Metaphysical Ecology: A Case Study.”

Environmental Ethics

15: 99–116.

Limitations on an Inclusive Definition of Ecosystem-Human Health

Documents

Transcript of Limitations on an Inclusive Definition of Ecosystem-Human Health