Category: Philosophical theories

Aristotle's criticism of Plato's theory of Forms

Aristotle carries out a systematic and rigorous critique of the theory of Forms. His basic objection is that Forms -both in their standard formulation, and in their mathematical version as it is exposed in the unwritten doctrines- do not have an autonomous ontological status, and they cannot explain change in the natural world.

Aristotle's principal objection

We wouldn't be much in error to presume that Aristotle, as with all of Plato's pupils, must have conceded to some version of the theory of Forms, when he was first initiated in philosophy. It seems, however, that he soon distanced himself from Plato's approach. This explains why he does not support the theory of Forms in any of his extant texts. Even in his early works, where he uses the person "we" in his references to the Platonists, he still puts up strong resistance against the existence and the functionality of the Forms. It is worth noting en passant that none of Plato's direct successors puts forward the orthodox version of the theory of Forms - which denotes how open to different opinions was Plato's school.

Aristotle disagrees primarily with the position that Forms belong to a separate realm of Being ("separate" beings) . If we subscribe to the platonic claim that the existence of every sensible entity clings on the existence of an independent Form (which the sensible imitates or partakes of), then we merely affirm a gratuitous "duplication" of the sensible world; for we have added nothing to its explanation. Platonic "participation" is, for Aristotle, a mere verbiage , and the "hypothesis" of the Forms is redundant. The only existing thing, for Aristotle, is the individual sensibles, that is, the particulars (kath' hekasta): the sun, this stone, Socrates etc. In his philosophy, the Forms translate into the "forms" (eidos). Nevertheless, the Aristotelian form is not a being exalted on the hyperuranium. On the contrary, it denotes the whole of predicates that define a particular being - which would not be what it is if it was deprived of these predicates. Every individual entity, every "substance" that is, is a compound of "form" and "mater" - it is a "mater in form".

Aristotle's critique

In his lost work On Ideas, Aristotle developed an analytical critique against platonic Forms. A summary of this critique is included in the lengthy and elusive 9th chapter in the First Book of his Metaphysics. There, the Forms do not take hold of the superior ontological level as they do in the platonic dialogues. Instead, they are mounted as derivative notions or entities that are imputed on two ultimate principles: the "One" and the "Indefinite Dyad". Forms are ontologically begotten through the participation of the Dyad in the One, and thereby they become identical to the ideal Numbers. The latter is a new category of "separated", intelligible beings that retain all the characteristics of the Forms, but hold out a mathematical nature. These professions belong to the so-called Plato's unwritten doctrines.

Aristotle's critique is epitomized in the following passage (where the reference "we" is made to Plato, his successors, and Aristotle himself).

"Above all we might examine the question what on earth the Forms contribute to sensible things; for they are not the cause of any motion or change in them... In general, although Wisdom is concerned with the cause of visible things, we have ignored this question (for we have no account to give of the cause from which change arises), and in the belief that we are accounting for their substance we assert the existence of other substances; but as to how the latter are the substances of the former, our explanation is worthless—for "participation," as we have said before, means nothing. And as for that which we can see to be the cause in the sciences, and through which all mind and all nature works—this cause which we hold to be one of the first principles—the Forms have not the slightest bearing upon it either. Philosophy has become mathematics for modern thinkers, although they profess that mathematics is only to be studied as a means to some other end" (Metaphysics 991a8-992b1).

The last sentence of the foregoing passage refers to the propaedeutic role assigned to the mathematical sciences in the 7th book of the Republic. Therefore, the text implicates Plato along with his successors. What Aristotle aims to impart to his students and companions is that, although "we" (that is, Plato and the circle around him as one philosophical movement) started by rightfully assuming the aim of philosophy to be the explanation of the observable phenomena, and by putting mathematics in their right position, "we" are now under the risk of eliminating philosophy by identifying it with mathematics.

Independent Forms are not involved in the natural world and its changes, and things get worse in the mathematical version of the theory. The philosophers of the Academy have superseded philosophy with mathematics, they have abandoned the study of nature, they have resigned from the determination of the causes of natural phenomena, and they neglect the purpose ("telos") of natural reality. Even the operation of the Forms as special causes of the sensible beings (an operation which Aristotle is ready to acknowledge) is obscured by the conversion of the Forms to numbers. For Aristotle, numbers only afford to define other numbers but not sensible beings. His conclusion comes naturally: "On this view the whole study of physics is abolished" (992b8-9). Therefore, the virtue of the existence of the Forms is outweighed by their vice.

Aristotle's anti-Platonism

For all that, it would be a mistake to charge Aristotle with an extreme anti-Platonism. In spite of his acute criticism, he endorses quite a few points from Plato's philosophy. Thus, he preserves at least one platonic Form in his ontology: the Unmoved Mover is pure form deprived of any mater, separated from sensibles, it is thought thinking itself (noesis noeseos). Likewise, in his epistemology, Aristotle follows the platonic thesis that "science" rests on the understanding of the universal. This affirmation results in an inconsistency in his own system, for that which exists is, for Aristotle, only the particular and not the universal.

Author: Vassilis Kalfas
  • Hayduck, M. ed. Alexander of Aphrodisias, In Aristotelis Metaphysica Commentaria, ed. M. Hayduck, Berlin 1891. Berlin, 1891.
  • Cherniss, H. Aristotle’s Criticism of Plato and the Academy. Bαλτιμόρη, 1944.
  • Fine, G. On Ideas. Aristotle’s Criticism of Plato’s Theory of Forms. Oξφόρδη, 1993.
  • Gerson,, L.P. Aristotle and other Platonists. Ιθάκα και Λονδίνο, 2005.
  • Jaeger, W. Aristotle. Fundamentals of the History of his Development , 2η έκδ. Oξφόρδη, 1948.
  • Leszl, W. Il ‘De Ideis’ di Aristotele e la teoria platonica delle idee. Φλωρεντία, 1975.
  • Ross, W. D. Aristotle's Metaphysics. A Revised Text with Introduction and Commentary. Oxford, 1924 - 2nd ed.1958.
  • Tredennick, H. Aristotle in 23 Volumes, Vols. 17, 18. Cambridge, London, 1933, 1989.
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