The First Great Platonist and Plato's First Great Critic

Aristotle, 384-322 BCE.

Raphael, The School of Athens Plato and Aristotle, the School of Athens
Plato points to a "higher" reality, the eternal realm of the heavens. Aristotle is younger, more worldly. His hand points forward, not to the heavens. Aristotle brings Platonism down from the heavens. He is a Platonist. Aristotle accepts what he regards as the central parts of Platonism, but he also is a critic. He eliminates what he regards as the excesses of Platonism.

Plato holds a copy of the Timaeus, a late dialogue devoted to cosmology. Aristotle holds a copy of the Nicomachean Ethics.
Aristotle is the second major philosopher in the Period of Schools.

He entered the Academy in 367 BCE when he was seventeen and remained there until 347 BCE, the year of Plato's death. Plato had tried to understand Socrates and the "love of wisdom" (φιλοσοφία) in terms of a certain view of human beings and their place in reality. After his death, it was left to subsequent philosophers to solve the problems and supply the details missing from the view Plato had set out. Aristotle is the greatest philosopher in this tradition.

The Aristotelian Corpus

The Aristotelian corpus is organized systematically, not chronologically. In contrast to the Platonic corpus, there is no chronological division into early, middle, and late works.

In this way, the Aristotelian corpus divides into three parts according to subject: the logical works, physical works, and ethical works. The logical works are first. They are followed by the physical works, which constitute the largest part of the corpus. The ethical works are last.

In addition, the works in the corpus are esoteric (as opposed to exoteric) works. They are written for members of his school, and some are little more than a series of notes that lack the explanation necessary for those who are not already familiar with the main lines of thought.

First and Second Philosophy

In the early dialogues, Socrates conceives of the "wisdom" (σοφία) in the "love of wisdom" (φιλοσοφία) as the competency involved in knowing how to live, but Plato subsequently uses the term φιλοσοφία with a more general meaning. In the Theaetetus, Socrates tells Theodorus that if were interested in Cyrene and its affairs, he would ask "whether any of the young men there are devoting themselves to geometry or any other form of philosophy (γεωμετρίαν ἤ τινα ἄλλην φιλοσοφίαν)" (Theaetetus 143d). In the Timaeus, Timaeus insists on the importance of "harmonics and every kind of philosophy (μουσικῇ καὶ πάσῃ φιλοσοφίᾳ)" (Timaeus 88c). In these passages, wisdom is a body of theoretical knowledge and φιλοσοφία is a discipline that aims to acquire it. This use of the term allows Aristotle to think of physics as "philosophy" (φιλοσοφία).
For Aristotle, there is "first philosophy" (πρώτη φιλοσοφία) and "second philosophy" (δευτέρα φιλοσοφία). He conceives of the subject he pursues in the physical works as second philosophy, and he understands first philosophy to be the legitimate offspring of Plato's conception of the love of wisdom and the life the lover of wisdom seeks in contemplation of the forms.

Aristotle's interest in second philosophy reinvigorates the philosophy of physics. This part of philosophy had emerged as part of the reaction to Thales and the Milesian inquirers into nature, but it was almost immediately receded into the background when Socrates called attention to "ethical" matters and "wisdom and truth and the best state of [the] soul." In the Timaeus, Plato returns to the philosophy of physics. Socrates no longer leads the conversation. Plato has Timaeus take the lead and work out the beginnings of a conception of the reality of natural bodies in terms of forms. Aristotle works within the general outlines of the framework Plato has Timaeus set out, but at the same time Aristotle also tries to remove problems he sees in this framework. It is in this way that Aristotle is both the first great Platonist and Plato's first great critic.

The Existence of Natural Bodies

Aristotle conceives of physics as the study of a certain kind of "being" or existence. This existence is the kind distinctive of natural bodies. Aristotle thinks that natural bodies possess a certain existence that distinguishes them as natural bodies. He understands this existence in terms of forms, but Aristotle conceives of forms differently from Plato. Aristotle conceives of the forms of natural bodies as particular objects. In the Metaphysics, The Metaphysics sits between the physical and the ethical works and hence is an exception to the three-part division of the corpus. It is also a work whose interpretation remains controversial. I accept the "Frede-Patzig" interpretation. (Michael Frede and Günther Patzig argue for this interpretation in Aristoteles "Metaphysik Z": Text, Übersetzung und Kommentar. Frede sets out the main points of the interpretation in a series of papers that he has collected in his Essays in Ancient Philosophy. The papers in this series originally written in German have been translated into English.) as will become clearer later in the course, Aristotle thinks there are no general objects and perhaps that nothing general exists at all.

In thinking that natural bodies have a certain kind of existence, Aristotle sets himself apart from the inquirers into nature. In their response to Parmenides, they rejected the existence of ordinary objects because they thought that nothing comes into or goes out of existence. According to Democritus, for example, only atoms and void are real. The various arrangements of the atoms in the void appear to human beings as natural bodies, but arrangements of atoms in the void are not themselves objects. They only appear as objects to those who rely on experience (as opposed to reason) to know what exists. Aristotle rejects this conception of the existence of natural bodies. He thinks that the natural bodies in the traditional conception of reality are real.

Aristotle's conception of the existence of natural bodies in terms of forms is not easy to understand in complete detail, but the project itself is straightforward. In this way, Aristotle returns to the issue of the "two kinds of existences, one visible [= sensible things], the other invisible [= the forms]" (79a) that Socrates introduces in the Phaedo. He thinks that natural bodies have a certain unity that persists through time. He thinks that the material that constitutes a natural body is organized a certain way and thus has a certain organization. This organization is what makes the material be a natural body and hence one thing as opposed to a heap of materials, and it is in terms of the ontology of forms that Aristotle explains what this organization and unity is.

Unity, Definition, and Demonstration

In this Aristotle follows Plato but also tries to correct what he regards the mistaken way in which Plato accounts for the existence of this unity and oneness of natural bodies.

"The philosophies described above were succeeded by the system of Plato, which in most respects accorded with them, but contained also certain peculiar features distinct from the philosophy of the Italians. In his youth Plato first became acquainted with Cratylus and the Heraclitean doctrines--that the whole sensible world is always in a state of flux (ἀεὶ ῥεόντων), and that there is no knowledge of it--and in after years he still held these opinions. And when Socrates, disregarding the physical universe (τῆς ὅλης φύσεως) and confining his study to ethical questions, sought in this sphere for the universal (καθόλου) and was the first to concentrate upon definition. Plato followed him and assumed that the problem of definition is concerned not with any sensible thing but with entities of another kind; for the reason that there can be no general definition of sensible things, as they are always changing (ἀεί γε μεταβαλλόντων). These entities he called Ideas (ἰδέας), and held that all sensible things are named after them and in virtue of their relation to them; for the plurality of things which bear the same name as the forms exist by participation in them" (Metaphysics I.6.987a-b).
For Aristotle, the unity or oneness of natural bodies is necessary for "knowledge" (ἐπιστήμη).

The unity, or oneness, of natural bodies of a given kind is specified in a definition. This specification is the essence (or "what it is to be" (τὸ τί ἦν εἶναι)) of bodies of the kind. This essence figures in a "demonstration" (ἀπόδειξις). Definitions are starting-points for demonstration. The definition specifies the essence of the species of the natural bodies under consideration. Demonstrations are deductive arguments (syllogisms) that demonstrate that these natural bodies have their specific behaviors because these bodies instantiate the essence specified in the definition.

Aristotle discusses demonstration in the logical works. These works are organized systematically. The Categories is first in the series. It discusses terms, the parts of sentences. On Interpretation is second. It discusses sentences, the parts of syllogisms. The Prior and Posterior Analytics are next. The Prior Analytics discusses syllogisms. The Posterior Analytics discusses demonstrations.

The physical works do not contain demonstrations. These works are investigations, not finished science, but the following demonstration (which is its basis in the Aristotelian idea that rational animal is the essence of man) indicates what Aristotle seems to have in mind:

Rational animals make discriminations in terms of sensation. (All M are P)
Human beings are rational animals. (All S are M)
Human beings make discriminations in terms of sensation. (All S are P )

In a syllogism, there are three terms: "subject" (S), "middle" (M), and "predicate"(P). Each premise has one term in common with the conclusion. In the major premise, it is the predicate term. In the minor premise, it is the subject term.

It is customary to write the major premise first. Aristotle writes "B is predicated of all A," not "All A are B." In this language, the example demonstration has the form

P is predicated of all M
M is predicated of all S
P is predicated of all S

"For if A is predicated of all B, and B of all C, A must necessarily be predicated of all C" (Prior Analytics I.4.25b).
This "syllogism" (συλλογισμός) displays some of the structure that belongs to bodies of the natural kind, human being. Each human being has a certain unity or oneness that persists through changes in the human being. This unity is specified formally in the definition of what a human being is. If some material is organized in the form of a rational animal, this material is not a heap. Material with this organization constitutes an enduring natural body. In particular, it constitutes a body with the power to make discriminations in terms of sensations. This power is a consequence of the organization of the material. The organization makes the material a human being. A human being, as a rational animal, has the power to make discriminations in terms of sensations.

Physics is Second Philosophy

Given this understanding of demonstrations, it is possible to see a little more clearly why Aristotle thinks of the subject he pursues in the physical works as second philosophy.

If the organization specified in the definition is the form of natural bodies of a given kind, then the thinking in physics is an example of the "contemplation" (θεωρία) that Plato suggests "happiness" (εὐδαιμονία) consists in most of all. Physics is thinking about demonstrations, and thinking about demonstrations is thinking about the forms specified universally in definitions.

This interpretation, however, does not show why Aristotle thinks of physics as "second" as opposed to "first" philosophy. The idea, it seems, is that the objects of the study in physics are second to the objects of first philosophy. Since the objects of the study are the forms of natural bodies, these forms are second to the objects of first philosophy. To get straight on what this means, it is necessary to take a closer look at what these forms are and also at Aristotle's ontology more generally.

Aristotle's ontology is not straightforward. Its explanation is an ongoing project in these lectures.

Reason, Knowledge, and Induction

Aristotle explains knowledge of the definitions that figure in demonstrations in a way that he thinks corrects a mistake in Plato. Like Plato, Aristotle thinks of a human beings in terms of the "soul" (ψυχή). Aristotle and Plato both accept the broad framework of this Socratic understanding of human beings. Aristotle rejects the ontological thesis in the Theory of Recollection that soul exists independently of the body. Aristotle, however, rejects the Platonic idea (in the Theory of Recollection) that the human soul preexists the body and that human beings are born with knowledge.

Aristotle accepts the epistemological thesis in the Theory of Recollection that "reason" is a matter of having certain concepts and the knowledge embodied in these concepts. Aristotle thinks that human beings naturally come to possess "reason" and the knowledge that belongs to "reason." This occurs in a causal process he calls "induction" (ἐπαγωγή). According to Aristotle, human beings first have "reason" not when they are born but when they acquire certain basic concepts about the world and the knowledge that these concepts embody.

Further details about how Aristotle understands induction are the subject of a subsequent lecture.

Perseus Digital Library:

Plato, Theaetetus, Timaeus
Aristotle, Metaphysics
Henry George Liddell, Robert Scott, A Greek-English Lexicon:
φιλοσοφία, philosophia, noun, "love of wisdom"

Arizona State University Library:
Loeb Classical Library:
Aristotle, Categories, On Interpretation, Prior Analytics, Posterior Analytics, Physics

"Aristotle wants to hold on to the metaphysical primacy of objects, natural objects, living objects, human beings. He does not want these to be mere configurations of more basic entities, such that the real things turn out to be these more basic entities. But to look at an object just as the configuration of material constituents transiently happen to enter into is to look at the material constituents as the more basic entities. So since Aristotle, against the view of practically all his predecessors, wants to hold on to the ontological priority of objects, he introduces essences which guarantee this status" (Michael Frede, "On Aristotle's Conception of the Soul," 146-147. Essays on Aristotle's De Anima, edited by Martha C. Nussbaum and Amélie Oksenberg Rorty (Oxford University Press, 1995), 93-107).

"Aristotle quite explicitly says (APo.[= Posterior Analytics] B19.100a2) that reason only comes into being as we acquire the appropriate concepts of things and thereby the knowledge of things and their principles whose mastery of these concepts embodies." (Michael Frede, "Introduction," 11. Rationality in Greek Thought, edited by Michael Frede and Gisela Striker (Oxford University Press, 1996), 1-28).

"Aristotle's own view seems to be that to recognize reason as something apart from perception would involve a recognition of the intellect (νοῦς) with its distinctive active power to grasp terms or universals and thus the basic terms and the immediate truths about them from which all other scientific truths can be deduced, a power which, though (at least in the case of human beings) causally linked to, and in a way based on, perception, nevertheless epistemologically is an independent source of knowledge, in fact the source of all knowledge properly speaking." (Michael Frede, "An Empiricist View of Knowledge: Memorism," 236. Companions to ancient thought 1.Epistemology, edited by Stephen Everson (Cambridge University Press, 1990), 224-250.)

"In [Posterior Analytics] B19, the crucial word 'logos,' finally does occur, namely in 100a2. It is used to refer to precisely the disposition of the mind or soul in virtue of which, or perhaps rather in which, we know first principles, and he talks of this disposition as something we come to acquire. I infer from this, though the conclusion seems striking and surprising (given our intuitions about, and our understanding of, reason), that Aristotle assumes that we are not born with reason, but acquire it, and that, in Aristotle's view, to have reason, to be fully rational or reasonably, is know first principles." (Michael Frede, "Aristotle's Rationalism," 169. Rationality in Greek Thought, edited by Michael Frede and Gisela Striker (Oxford University Press, 1996), 157-173).

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