The Legacy of Ancient Greek Philosophy

Prof. Rob KoonsEdward Feser, The Last Superstition: A Refutation of the New

Atheism, Chapter 2Leadership for America 2013

Socrates vs. The Sophists

Socrates (469-399 B.C)

Opposed the Sophists (the Wise Men), who tended toward skepticism and relativism (“Man is the measure of all things”).

Socrates used rational dialogue in order to seek the essences or “definitions” of things, especially ethical ones, like Justice, Courage or Friendship.

Plato’s Theory of “Forms”• A “Form” is the kind of essence that Socrates

sought: the Form of Justice, the Good, Humanity, etc.

• Forms are not physical objects, nor something private, subjective or merely mental. A “third realm”.

• Examples: mathematical objects, like the triangle.• For Plato, material objects (including us) are faint,

imperfect copies of some perfect Form.• This fact has normative implications: something is

a better F the more perfectly it copies the form of the F. Better triangles, better men.

• In modern philosophy, Plato’s Forms are classified as “abstract objects”. They are typically called “universals”.

Why believe in Forms or Universals?1. The “One over Many” argument. All triangles share something in common,

even if this common element were never recognized or thought of. It could exist even if all “instances” of it (physical triangles) were destroyed.

2. Such abstract objects are studied in mathematics, which studies real things but not physical things.

3. The nature of propositions (truths and possible truths). These would exist and could be true even if they were no material objects and no minds.

4. The argument from science. All sciences investigate universal laws, which are not about particular things but about their common natures.

5. Language necessarily involve universals. A word or word-type (like “red”) is itself a universal, instantiated by many physical and psychological tokens. There are sentences in English that have never been and never will be spoken, and yet which have definite meanings.

6. The objectivity of concepts and the possibility of storing and communicating knowledge. We cannot literally share our ideas nor store them – all we can remember or communicate are universal contents.

The Philosophy of Aristotle

Aristotle (388-322 BC) was Plato’s student.

Influenced all later Christian philosophers, including Augustine and Thomas Aquinas.

Wrote on many subjects: biology, chemistry, astronomy.

Best-known: Categories, Metaphysics.

“Moderate” Realism about Universals

• Aristotle agreed with Plato that universals (forms) must exist to make science and thought possible.

• However, he rejected the idea that material objects were mere “copies” of separately existing Forms.

• Instead, he insisted that the Forms existed “in” particular objects. A universal (like humanity or justice) exists only insofar as there actual humans or just people.

Species and Genus

Genus

Differentia 1 Differentia 2

Species 1 Species 2

The Ten Categories

• Substance• Quantity• Quality• Relation• Place• Time

• Position (attitude)• State (having)• Action• Affection (having

been acted on)

Primary vs. Secondary Substance

• Reverses Plato’s priorities: it is the (changeable) particular substance that is most real (most fully substantial).

• Secondary substances are substantial only in a “qualified way”: by referring to classes (natural kinds) of substances.

• Species are more fully substantial than genera, because closer to individuals.

Substance vs. Accidents

• Besides substance, the other categories (quantity, quality, relation, etc.) are categories of ‘accidents’.

• Individual accidents are “present in” substances, in such a way that there is a one-way dependency of the accident on its substantial bearer.

• Aristotle: “Humanity is not present in the individual man.” Why not? Is there such a thing as Socrates’ humanity?

Four-Fold Division

Not predicated of a subject

Predicated of a subject

Not present in a subject

Particular substances

Substance universals (species, genera)

Present in a subject

Particular accidents

Non-substantial universals

The Fourfold Division (2)

Not predicated of a subject

Predicated of a subject

Not present in a subject

Socrates, Bucephalus

Humanity, animality

Present in a subject

Socrates’ paleness

Paleness

The Possibility of Change

• “It is a distinctive mark of substance, that, while remaining numerically one and the same, it is capable of admitting contrary qualities (accidents), the modification taking place through a change in the substance itself.”

• Example from Physics, 1: “the unmusical man becomes musical.”

Denials of the Possibility of Change

• Denied by Parmenides and his disciples (the Eleatic philosophers).

Denials of the Possibility of Change

• Argument from the causal impossibility of change.

– Any new thing must come from either being or non-being.

– If it comes from being, it already exists, and so isn’t new.

– Nothing can come from non-being.– Consequently, no new thing can come to

be.

Potential and Actual Being

• Aristotle rebuts these arguments by introducing a distinction between two kinds of being: potential and actual.

• To speak or think of a thing, it must have at least potential being, not necessarily actual being.

The Causation of Change• Change comes from both being and non-being (in

different ways).• For a change to occur, there must be something

that exists before and after the change (the substance).

• There must also be the absence or privation of some accident (e.g., being non-musical).

• The non-musical man becomes musical (i.e., a musical man). Change begins with a combination of being (as a substance) and non-being (of an accident in the substance).

Causation Requires an Agent

• When change happens, there was already a potentiality for the new state in the changing thing.

• Potentialities for new states are rooted in the actual nature of a thing, not just in what we can imagine or conceive of.

• In addition for a potentiality for change in the thing that changes (the “patient”), we also need an outside “agent”, with an active power of producing the change.

• This “agent” must exist separately from the “patient”, or else we could not explain why the change did not happen sooner: the change happens only when the agent and patient come into mutual contact (or appropriate proximity) with one another.

This Applies also to Animals and Persons

• Animals and people may appear to act spontaneously, with no external agent, but we can in fact always find an agent-patient pair.

• In many cases, the organism is stimulated into action by some perceived change in the environment.

• In ever case, we can find some part of the organism acting upon some other part: such as molecules in the in the stomach or heart acting upon neurons, which in turn act on the brain, stimulating further behavior through perception of some internal state.

Potentialities always Depend on Actuality

• In a sense, these are complementary notions.• However, actuality is more fundamental than or “prior to”

potentiality, in several ways:• The potentiality of a thing is always grounded in its

actual nature.• A potentiality is always a potentiality for some kind of

actuality, not vice versa. Actuality is prior in definition.• Potentialities are never actualized except by the

presence of actual agents.• As a consequence, a being of pure actuality is possible,

but not a being of pure potentiality.

Proof of God’s Existence: St. Thomas Aquinas’s “First Way”

• In his writings (Summa Theologica and Summa Contra Gentiles), St. Thomas draws on Aristotle’s work to demonstrate the existence of God as the First Agent, a being of Pure Actuality (with no unrealized potentialities).

• Time cannot pass without change, and change cannot happen without the activity of agents.

• When natural, created agents act in time, they pass from being potentially active to being actually active, from potentially in contact or proximity with the patient to being actually so.

• Hence, there must always be some “prior” agent that actualizes this potentiality of the proximate natural agent.

Aquinas’s First Way

• There cannot be an infinite series of such agents, each being actualized by the prior one, with no first agent, since nothing would explain how the whole series moved from potentiality to actuality

• Thus, there must be a first agent which is always active and always in contact with every created thing, the ultimate source of all change, and the ultimate driver behind the forward motion of time itself.

• Such a first agent must be omni-present (present everywhere) and immaterial, and it must be a being of pure actuality, with no unrealized potentiality.

• Such a being must be “beyond” time, influencing creation by its thought and intention. This must be God.

Isn’t Inertia the Answer?

• Some philosophers argue that Newton’s idea of inertia is the answer: once in motion, bodies tend naturally to stay in motion. No First Agent/Mover must continuously keep them moving at every instant.

• Why this is wrong: inertia presupposes the passage of time. Things tend to move with a constant velocity: covering the same distance in equal intervals of passing time.

• Thus, inertia cannot explain why change keeps happening, why time keeps passing.

• For this, you need an eternally active, timeless Mover.

The Necessity of Stability

• Heraclitus had said: “All is flux,” and “You can’t step twice into the same river.” Suggesting that nothing whatsoever endures from one moment to the next.

• Aristotle argues that this is impossible. Change implies that something is changed: the thing changed must in some respects endure.

• In simple case: substances endure, accidents change.

What about Substantial Change?

• There are two kinds of change that don’t fit Aristotle’s simple model (as presented in The Categories): generation (creation), and destruction of substances.

• Aristotle believed that some substances: plants, animals, perhaps blobs of pure element or mixture, do come into and go out of existence.

Aristotle’s Physics, Chapter 1

• In this chapter, Aristotle introduces the notion of ‘matter’ (hule -- lumber).

• Matter = “the primary substratum of each thing from which it comes to be without qualification (I.e., from which it is generated), and which persists in the result (after the thing is destroyed).”

• Substratum = that which endures through a change.

In what sense does the matter endure?

• Not as actual substance.• For Aristotle, one substance cannot be

composed of, constituted by another substance or substances. A substance is a thing that exists in and of and by itself, not through the existence of other things.

A simple illustration

Particle A

Particle B Particle A

Actuality

Potentiality

Generating a Complex Individual

B complex A Particles

Actuality

Potentiality

A Particles

Parts are Essentially Parts

• The parts of a substance (such as an animal or plant) are essentially parts: they can exist only as the organic parts they are. Organic things are organic all the way down.

• Thus, when the animal consumes food, water or oxygen, even the microscopic particles cease to exist and are replaced by corresponding organic parts.

• When waste is eliminated, the converse process takes place. Ditto for conception & death.

Aristotelian Matter is Hierarchical

• The residue which would exist at the animal’s death is the proximate matter of the animal.

• What if those substances were also destroyed? Then some further substances would exist - the more remote matter of the animal.

• At the ideal limit -- we would reach “prime matter”.

What would Prime Matter be Like?

• It can never exist as such. Aristotelian matter always exists in some form or other.

• It is much closer to modern ideas of energy (or mass-energy) than to Newton’s or Boyle’s conception of “matter”.

• It lacks even dimensionality and quantity.• It’s what “survives” through radical

transformations of energy from one form (and even one quantity) to another.

Form and Matter

• Aristotle’s view is called ‘hylomorphism’ (or ‘hylemorphism’).

• Substances are “composed” of both form (morphe --- the same word Plato used) and matter (hule -- Aristotle’s coinage).

• Socrates’ humanity is his form: that by which Socrates exists, that by which his matter is his matter (as opposed to an actual corpse).

Form is the Actuality; Matter is Potentiality

• The “matter” of a substance is its potentiality to produce new substances, either by extruding parts of itself, or by being utterly destroyed and leaving behind some residue of itself.

• The “form” of a substance is its actual nature, here and now. The form explains what active powers and passive potentialities a thing has.

• This is why a being of pure actuality, like God, must be immaterial.• Just as actuality is prior to potentiality, so form is prior to matter.• Thus, it is possible for a substance to exist as pure Form (God, the

angels, the human soul after death and before the resurrection), but it is impossible for anything to exist as pure, unformed Matter.

The Four “Causes”

• The Material Cause: what is a thing made of?• The Formal Cause: what is the fundamental nature of a

thing? What is it?• The Efficient Cause: what agent brought this thing into

existence?• The Final Cause: what is the end or purpose for which

the thing exists?• These obviously apply to human artifacts, tools.• Also to organs.• Aristotle argues that all four apply universally, to all

substances.• The most controversial is the last one.

Final Causation

• In the inorganic world: consider cycles, like the water cycle or rock cycle. Each stage exists “for the sake of” the next one.

• The basic laws of nature are not just regularities (Nancy Cartwright). They represent the ways things (electrons, photons) act, their active powers and passive potentialities.

• Powers and potentialities point forward, to a possible future. This is the final cause. Aquinas: “Every agent acts for an end, otherwise one things would not follow from the action of the agent more than another.” (ST I, q44, a4)

• Final causation is the “cause of causes”, the fundamental basis for all explanation.