Ancient Philosophy

6. The Atomists

Overview

• The Early Pluralists– Empedocles– Anaxagoras

• The Later Pluralists: The Atomists– Leucippus & Democritus– Democritus’ Legacy

• Materialism• Reductionism• Mechanism

Eleatic Philosophy& its Pluralist Rivals

• The Theses of Eleatic Philosophy– There is no void, as a consequence of which

• Monism: There is no plurality.• There is no motion.

– There is no change: • There is no generation & corruption.• There is no alteration (qualitative change).

• The pluralists are committed to refuting the arguments for these theses (or at least to building up defensible alternative systems).

– One should distinguish two groups here• The Early Pluralists—Anaxagoras & Empedocles• The Atomists—Leucippus & Democritus

3

The Atomists

• Leucippus (Λεύκιππος) (early C5 BC)– All sources cite Leucippus as founder of this doctrine, but not

a lot is known about him & there is not always much point in trying to distinguish him from his disciple.

• Democritus (Δημόκριτος) of Abdera (460-370)– We have more material from Democritus, who must be judged

the most prominent of the early atomists• Later atomism becomes an element of Epicureanism.

– So, a good later source of the doctrine is Lucretius’ De Rerum Natura (95-55 BC).

Atomist Epistemology(Theory of Knowledge) I

• There are two kinds of knowledge:

1. Obscure sense-knowledge. This is knowledge of the ordinary properties of ordinary objects (e.g., of the color of a flower). This knowledge comes from the senses. Why is it obscure?

2. Genuine knowledge. This is knowledge of fundamental objects (i.e., of the atoms). This knowledge comes from reason, the “finer means.”

• The argument for the relative obscurity of sense-knowledge.

Anything that shifts its character according to the body’s dispositions, influences, and confrontations

is obscure.

Sense-knowledgeshifts its character according to the body’s dispositions, influences, and confrontations.

Sense-knowledge is obscure.

[All]

So, [All]

Atomist Epistemology II

• The role of the senses– Limited

• “By convention there is sweet, by convention there is bitter, by convention hot and cold, by convention color; but in reality there are only atoms and void.”

– But necessary• “A dialogue between the intellect and the senses:

– Intellect: It is by convention that color exists, by convention sweet, by convention bitter.

– Senses: Ah, wretched intellect, you get your evidence only as we give it to you, and yet you try to overthrow us. That overthrow will be your downfall.”

Atomist Ontology(Theory of Being)

1. There are two fundamental principles, each grounded in a distinction:1. “The existence of the non-existent”

• The distinction is between • two kinds of space

• the full &• the empty

• (or) two kinds of being• atoms (matter) &• the void

2. Ordinary objects are made of very small particles [atoms] (reductionism).• The distinction is between

• ordinary objects &• indivisible [i.e., atomic] particles

The Void:“The Existence of the Non-existent”

• This makes both pluralism & motion possible, as both Eleatic arguments depended on the claims that:– non-being does not exist– empty space is non-being

• What kind of argument can Democritus give for his view?

What Democritus & Parmenides agree on:

[motion] ↑ [the non-existence of non-being] “p ↑q” means “not both p & q”

To this Democritus adds: Motion occurs. Parmenides affirmed the other proposition

So, he concludes: [the non-existence of non-being] is false At least as Parmenides understood it (in its denial of a void)

Experimental Evidence forthe Existence of a Vacuum

• For, the Greek atomists,– the assertion of the existence of a vacuum has explanatory power– but its existence could not be shown more directly

• The experimental creation of a vacuum was first accomplished by Otto von Guericke of Magdeburg in the 1650’s.– He pumped the air out of a device made of two copper hemispheres, after which

even two teams of horses could not pull them apart.

Democritean Atoms

• Indivisible (by definition)• Immutable

– including ingenerable & incorruptible• Many (= Quantitative Pluralism)• Identical in kind (= Qualitative Monism)

– i.e., they all have the same properties– though they differ from one another in

• size (as N vs. N)• shape (as N vs. H)• orientation (as N vs. Z)• arrangement (as DOG vs. GOD)

• Movable– hence, rearrangeable

• this is what makes change possible in ordinary objects

10

Democritean Atoms & Parmenidean Being

• Atoms are like Parmenidean Being in some ways.– Each atom is

• indivisible – hence the name “atom”

• unchangeable– since change was rearrangement of parts and atoms don’t have parts

• ingenerable & incorruptible• They are unlike it in others.

– Unlike Parmenides’ atoms• There are many (Quantitative Pluralism) • They are mobile

– the existence of the void allows for this

Democritean Atoms &the Atoms of Modern Science

• Democritus’ atoms are different in important ways from the atoms of contemporary science.– Democritean atoms

• They do not differ from one another in kind, but only in– size & shape (as N vs. H) (Qualitative Monism)– orientation (as N vs. Z)– arrangement (as DOG vs. GOD)

• They are indivisible.• They do not change.

– The atoms of modern science • They differ from one another in kind: Carbon vs. Oxygen.• They are divisible.

– They have parts (protons, neutrons, electrons) which (in the case of nucleons) are themselves further divisible

– They can be split (in nuclear fission)• They are changeable.

– In radioactive decay, an atom of one element becomes an atom of another.

Ordinary Objects

• Ordinary objects (the objects of sensible experience) are – (trivially) like atoms

• many &• moveable

– (importantly) unlike atoms, also• composite• divisible (into atoms), &• changeable (by rearrangement of atoms).

Differences in Ordinary Objects:Diamonds & Graphite

14

Differences in Ordinary Objects II

15

Two Theories of Change

1. Parmenides & the Replacement Theory of Changea. Parmenides presents the Replacement as the only possible mode of

change.• Change is the ceasing to exist of one thing & the generation of another

thing in its place.b. Change by replacement, he says, is impossible.

2. Democritus’ Rearrangement Theory of Changea. Coming to be is an aggregation of parts.b. Passing away is a dissolution of parts.c. Change is a rearrangement of parts.d. All of these are possible.

Democritus’ Reply to Parmenides:1. Motion

Parmenides’ Argument Democritus’ Objections

(1) If things move, then there must be an empty place to which things can move.

(2) If there is an empty place to which things can move, then there must be places in which there is nothing [“non-being”].

(3) If there are places in which there is nothing [“non-being”], then non-being exists.

“Non-being” here must mean empty space.

(4) That non-being exists is absurd. But that empty space exists is not absurd. (Cf. F1, T4)

∴ (5) Things do not move.

Democritus’ Reply to Parmenides:2. Change

Parmenides’ Argument Democritus’ Objections

(1) If change occurs, then something non-existent comes into existence.

(2) Non-existent things do not exist. The arrangement that constitutes the ordinary object does not exist;but the atoms that make it up do.

(3) What does not exist cannot do anything. Since the atoms exist, they can rearrange themselves.

(4) What can’t do anything can’t come into existence. Since the atoms can rearrange themselves, the ordinary object can come into existence.

∴ (5) Non-existent things can’t come into existence.

∴ (6) Change does not occur.

Democritus on Life

• Life in general– The question—what gives some things the powers we call “life”?

• In particular, motion (both growth & local motion) & perception• Democritus focusses on motion (as did Thales).

– Life-motion is made possible by a particular size & shape of atom• “Soul atoms”—small, mobile, & dispersed throughout the body• Their presence makes a body alive• Their mobility causes the motion we call life• At their departure, the body becomes dead

• Human life– Distinctive human powers—No Democritean account survives.– Immortality

• Soul atoms are neither created nor destroyed• But they disperse at death• There is no aggregate of soul-atoms that continues to exist as “you”

Contrasts among the Pluralists

• The early Pluralists share the view that there are many things of many kinds. They differ in that – Empedocles maintained that there are many things but only four basic kinds.– Anaxagoras, that there are an infinite number of things of an infinite number of kinds.– The Atomists, that there are an infinite number of things of one kind, though differing in size,

shape, and arrangement.• Reductionists distinguish between the objects of ordinary experience and the fundamental realities of

which they are composed (to which they can be reduced). Ordinary objects can be generated or destroyed or changed; the component parts cannot.– Empedoclean Reductionism

• There are four kinds of elements.• There are no smallest (indivisible) particles.

– Democritean Reductionism • There are smallest (indivisible) particles.• All particles are of a single kind.

– Anaxagoras’ Non-reductionist alternative:• Homoeomereity: The parts of any thing are of the same type as the whole.

– This is non-reductionist.• Universal Mixture: Every thing includes parts of every kind of thing.• Predominance: The kind of thing an ordinary object is is determined by which of the parts

predominate.

The Eleatics & the Pluralists

Is there a void? Is there one thing or many?

Is motion possible?

Can things be generated or destroyed?

Can things change (be altered)?

Eleatics No One No No No

Empedocles

No

Many things of four kinds

Yes Ordinary things—Yes

Yes

Anaxagoras

No Many things of many kinds

Yes Ordinary things—Yes

Ordinary things—Yes

The Atomists (Democritus &

Leucippus)Yes Many things of

one kind (atoms) YesOrdinary things

—YesAtoms—No

Ordinary things—Yes

Atoms—No

The Eleatics & the Pluralists (cont’d.)

Is there one thing or many? Generation & Destruction? Change?

Eleatics Quantitative & Qualitative Monism No No

EmpedoclesQuantitative & Qualitative Pluralism

Ordinary things—Yes;Ordinary things—Yes;

AnaxagorasQuantitative & Qualitative Pluralism

Ordinary things—Yes;Ordinary things—Yes;

The Atomists Quantitative Pluralism & Qualitative Monism

Ordinary things—Yes;Atoms—No

Ordinary things—Yes;Atoms—No

Democritus’ Legacy

NB: Three closely related ways of looking at his significance for contemporary philosophy.

1. Materialism- No non-material things exist

• perhaps in general- no God or angels

• but especially as components of ordinary objects (e.g., man)- No Aristotelian or Platonic forms- No non-material souls

2. Reductionism- Ordinary objects are nothing but collections of atoms.

3. Mechanism- There is no difference in kind between organisms & machines.- Living things can be analyzed by the same principles used in the analysis

of organisms.

The Relation among the ThreePoints of the Legacy

• Materialists might be either– Non-reductionists– Reductionists, who might be either

• Mechanists (thinking that ordinary objects can be reduced to machines)• Non-mechanists (thinking that ordinary objects can be explained in

terms of their parts [i.e., be reduced] but not to machines)

Non-ReductionisticMaterialism

Non-MechanisticReductionism

MechanisisticReductionism

ReductionisticMaterialism

Materialism

Democritus & Mechanism

• Strictly, the idea of reducing human physiological & psychological processes to machines was not an idea of Democritus.– The kinds of machines used in classical Greece did not lend themselves to

such a comparison.• But early modern thinkers—two in particular—can be seen as extending

Democritus’ legacy in a natural direction.1. René Descartes’ mechanistic physiology

• Man (1630-33; publ. 1662)2. Julien Offray de la Mettrie’s mechanistic psychology (a comprehensive

mechanistic anthropology)• The Man-Machine (1748)

Cartesian Physiology

• Descartes was not a materialist– nor a comprehensive mechanist

• He made a sharp distinction between– physiological processes, which he interpreted

mechanically, &– psychological processes, which he thought were

• unique to man & • spiritual rather than mechanical

The Inspiration for Descartes’ Mechanical Physiology

• Tommaso Francini (1571–1651), Florentine hydraulic engineer

• a contemporary description of his work at the Villa Medicea di Pratolino in Tuscany

– “At Pratolino, the statues turn about, play music, jet streams of water, are so many and such stupendous artworks in hidden places, that one who saw them all together would be in ecstasies over them.”

• He came to France in 1597, where he built the grottoes of Château-Neuf in St.-Germain-en-Laye for King Henry IV & his Medici queen

– These gardens included elaborate hydraulic automata, e.g., a figure of Perseus which descended to slay a dragon that arose from a basin of water

– Descartes would have seen these gardens

De La Mettrie & the Man-Machine

• Descartes defended a dualist anthropology:– A material body, a machine that carried

out physiological functions (such as digestion, respiration, & growth).

– A spiritual mind (or soul), which was not mechanical & carried out psychological functions such as perception, emotions, choice & thought.

• De La Mettrie extended the mechanical analysis of human functions from the physiological to the psychological.

Mechanical Analysis:A Complex Machine

• All complex machines are combinations of simple machines.– This derrick combines a wheel & axle with a pulley.

Six Simple Machines (cont’d.)

<Inclined Plane

Lever>

<Wedge

Wheel & Axle>

<Screw

Pulley>

Mechanical AnalysisReduction of the Six Simple Machines to Two

• Simple machines are used to transform forces, either– changing their direction– or changing the magnitude of the force.

Machines dependent on the vector

resolution of forces

Machines in which there is an equilibrium

of torques

The Analytically Simplest Simple Machines 1. The inclined plane 4. The lever

Versions of the Simplest Machines

2. The wedge—a moving inclined plane

5. The wheel and axle—a lever that can turn 360°

More Versions 3. The screw—helical inclined plane 6. The pulley

Mechanical Analysis:Three Kinds of Lever

• A lever, by definition, is a rigid bar that pivots on a fixed point (the fulcrum).– Its mechanical effects are produced by applying an effort at one point on

the bar– and benefitting from the way the bar pushes on a load at another point.

First Class Lever(Load—Fulcrum—Effort)

E.g., pliers

Second-Class Lever(Effort—Load—Fulcrum)

E.g., a nutcracker

Third-Class Lever(Load—Effort—Fulcrum)

E.g., tweezers

A Mechanical Analysis of a Human Being I:The Arm as a Lever

• The arm as a lever.– The analysis of levers is based on the

relative position of fulcrum, effort & load.

– The arm as a lever• The elbow is the fulcrum.• The effort is applied where the

muscle is attached to the bone of the forearm.

• The load is usually placed on the hand.

• So, the order is F—E—L, which makes the arm a 3rd Class Lever.

A Mechanical Analysis of a Human Being II:The Body as an Automobile

• (N.B. auto + mobile = self-mover)• The arm is more than just a lever.

– It also has an engine (the muscles) & a fuel tank (the stomach).• So, it is more like a machine that has an engine & a fuel tank, e.g., a car.

– An engine converts another form of energy (here, chemical energy), into mechanical energy (motion).

A Mechanical Analysis of a Human Being IIIa:The Mind as a Computer

• Automobiles may move themselves, but they do not drive themselves.– Perhaps the human being is not just an automobile, but an automaton (like

a robot or a Tomahawk cruise missile).

TERCOM = Terrain Contour MatchingDSMAC = Digital Sense Matching Area Correlation

A Mechanical Analysis of a Human Being IIIb:The Mind as a Computer

• The human brains is a network of neurons.• In 1943, Warren McCulloch & Walther Pitts imagined an artificial neuron, which could

be built mechanically.• The work of Alonzo Church & Alan Turing suggested that for any effective input-output

function, one can build a Turing machine that can take that input and produce that output.• So, if human behavior is such an IO function, it can be duplicated by a machine.

Structure of a McCulloch-Pitts Artificial Neuron

input weights weighted sum

function of activation output

Summary

• Democritus thus laid the foundations for a philosophy of nature (& of man) that has persisted down to our own day.

• Two alternatives are more prominent in ancient philosophy– Plato’s Idealism– Aristotle’s Hylomorphism