The First Great Platonist and Plato's First Great Critic

Plato, 427-347 BCE.   Aristotle, 384-322 BCE.

Raphael Sanzio da Urbino (1483-1520), The School of Athens
Plato and Aristotle, the School of Athens
Plato points to a "higher" reality. Aristotle points forward, not to the heavens. He accepts what he regards as the central parts of Platonism, but he also is a Platonic critic. Aristotle 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 in the view Plato developed. 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 the Aristotelian corpus, the division is according to subject matter: the logical works, physical works, and ethical works. The logical works are first, followed by the physical works, which constitute the largest part of the corpus. The ethical works are last.

The works in the Aristotelian 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.

The systematic organization of the Aristotelian corpus and the esoteric character of the works makes it difficult to know what to read first to understand what Aristotle thought.

How to Approach the Corpus

The Physics is the first work in the physical works. Books I-IV discuss nature. Books V-VIII discuss motion.

Second philosophy is second to "first philosophy" (πρώτη φιλοσοφία). Aristotle discusses first philosophy and its relationship to second philosophy in the Metaphysics.

In the traditional organization of the corpus, the Metaphysics sits between the physical and the ethical works and hence is an exception to the three-part division of the corpus.

The Metaphysics is 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. In this book, the papers Frede wrote in German are translated into English.
The approach in these lectures is to begin with a subject Aristotle discusses primarily in the physical works and that he calls "second philosophy" (δευτέρα φιλοσοφία).

Second philosophy is about the existence of natural bodies. An interest in their existence emerged as part of the reaction to Thales and the Milesian inquirers into nature, but it was almost immediately pushed into the background when Socrates called attention to "wisdom and truth and the best state of the soul." Later, in the Timaeus, Plato gives new life to the interest in natural bodies and their existence. Timaeus now, not Socrates, leads the conversation and works out the beginnings of a conception of natural bodies in terms of forms, the receptacle, and the demiurgos. Aristotle works within the general outlines of the framework Timaeus sets out, but he also tries to remove problems he sees in this conception.

The Existence of Natural Bodies

Aristotle conceives of natural bodies as having a certain kind of "being" or existence that distinguishes them as natural bodies as opposed to other kinds of things. Aristotle understands this existence in terms of forms, but he conceives of forms differently from Plato.

In thinking that natural bodies have a certain kind of existence, Aristotle sets himself apart from the way the inquirers into nature responded 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 arrangements of the atoms in the void appear as natural bodies, but these arrangements 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.

Aristotle's conception of the existence of natural bodies is not easy to understand in detail, but the approach he takes is relatively straightforward.

He thinks that natural bodies possess a certain oneness or unity that persists through time. He thinks that the material that constitutes a natural body is organized a certain way. He thinks that this organization makes the material be a natural body of a given kind. Without the organization, there is a heap of materials, not a natural body. Aristotle tries explain the existence of this organization as a form.

How the existence of this organization is a form will become a little clearer in subsequent lectures, but some insight is possible now by seeing that Aristotle understands physics to consist in "demonstrations" and demonstrations to be about the forms of natural bodies.

Unity, Definition, and Demonstration

"In his youth Plato first became acquainted with Cratylus and the Heraclitean doctrines--that the whole sensible world is always flowing (ἀεὶ ῥεόντων), and that there is no knowledge of it--and in after years he still held these opinions. And when Socrates, disregarding world of nature 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. 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). Aristotle thinks that the unity or oneness that characterizes the existence of natural bodies is necessary for there to be "knowledge" (ἐπιστήμη) about these natural bodies.

This knowledge is set out in what Aristotle calls a "demonstration" (ἀπόδειξις).

Definitions are starting-points for demonstrations. Definitions specify the unity or oneness of natural bodies of a given kind. This specification is the "essence" (or "what it is to be" (τὸ τί ἦν εἶναι)) of these bodies. The definition specifies the essence of the species of the natural bodies, and a demonstration is a deductive argument (a "syllogism" (συλλογισμός)) that shows that these natural bodies have their specific behaviors (the behaviors that belong to the kind of the natural body) because these bodies instantiate the essence specified in the definition.

Aristotle discusses demonstration in the logical works. Like the Arisotelian corpus generally as we now have it, the logical 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 follow On Interpretation. The Prior Analytics discusses syllogisms, and the Posterior Analytics discusses demonstrations.

"The starting-point of every demonstration is the what it is" (On the Soul I.403a).

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

It is customary to write the major premise first. This can seem unnatural until one realizes Aristotle does not write "All M are P." He writes "P is predicated of all M." When the premises and the conclusion are expressed in the language Aristotle uses, the demonstration

All M are P
All S are M
All S are P

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).
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 )

This syllogism displays some of the structure that belongs to the bodies in the natural kind human. Each human being has a certain unity or oneness that persists through change. This unity is specified formally in the definition of what a human being is. If material is organized in the form specified in the definition, then this material is not a heap. Rather, the material constitutes an enduring natural body. In particular, it constitutes a body with the power to make discriminations in terms of sensations. The body has this power because of the organization of the material as a rational animal. As a rational animal, the material is organized in a way that gives the body the power to make discriminations in terms of sensations.

The Life of Contemplation

Given this understanding of demonstrations and the necessity of forms for the definitions that are starting-points for 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 the natural bodies of a given kind, then it seems that the knowledge in physics is an example of what one thinks about in the activity of "contemplation" (θεωρία). Physics consists in demonstrations, and thinking about these demonstrations is thinking about the forms specified in the definitions.

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

Reason, Knowledge, and Induction

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

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.

How he understands induction is a subject of a subsequent lecture.

Perseus Digital Library:
Plato, Theaetetus, Timaeus
Aristotle, Metaphysics

Henry George Liddell, Robert Scott, A Greek-English Lexicon:
ἀπόδειξις, apodeixis, noun, "showing forth, making known, exhibiting"
φιλοσοφία, philosophia, noun, "love of wisdom"
συλλογισμός, noun, "computation, calculation"

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 [as they are for the inquirers into nature], 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" (Michael Frede, "On Aristotle's Conception of the Soul," 146. Essays on Aristotle's De Anima, 93-107).

"In [Posterior Analytics] B19, the crucial word 'logos' [λόγος], finally does occur, namely in 100a2. "[S]o that some come to have reason (λόγον) ... and others not" (Posterior Analytics II.19.100a).

The Loeb translator (in the link) obscures the point.
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, 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, 157-173). "Aristotle quite explicitly says (APo. 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, 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, 224-250).

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