“To be a Platonist is to favor the abstract, perfect truths of mathematics and logic as a model to be followed by all fields of knowledge by the ideals of moral and political life; it is to be more concerned with attaining perfectly certain, logically unified knowledge (the ladder of knowledge and ideals (the life of reason) than with the practical question of how such knowledge and ideals can relate to the concrete changing actualities of existence. To be an Aristotelian is to favor the concrete, particular changing things of nature and human life (plants, animals, human beings, states of various types), taking biology as a model for understanding their genesis and developmental stages as well as the factors of influencing their growth or decay; it is to be more concerned with gathering knowledge of actual things than with the logical unification of knowledge; more concerned with the ideals which are realizable by kinds of things within their particular circumstances than in ideals of excellence which are separate from and transcendent of the actualities of nature and human life.
These differences between Plato and Aristotle–philosophical and temperamental–are best exhibited by Aristotle’s devastating criticism of Plato’s theory of forms. For Plato, as we have seen, the immutable, eternal forms constitute reality and are transcendent of the sensible world of flux, of changing things which constitute mere appearance. Aristotle claims the very opposite: it is the concrete, individual things that are real– particular plants, animals, men, and states. Aristotle calls such particular things substances. Metaphysics, which is the study of the nature of reality, is for Aristotle the study of individual concrete substances. Aristotle attacks
- Plato’s theory of forms with a barrage of arguments, the principal points which are:
- Plato’s theory of forms claims to explain the nature of things but in fact the abstract forms are only useless copies of actual things, and fail to provide any explanation of the existence and changes of concrete things; Plato’s theory of forms sets up an unbridgeable gap, a dualism between the world of intelligible ideas and the world of sensible things; the theory makes it impossible to explain how sensible things and intelligible forms are related at all.
Does Aristotle then reject forms as mere illusions? Not at all. Aristotle appears to have been a committed follower of Plato’s theory of forms during his twenty years at the Academy, and the Platonic influence remains strong. Aristotle’s attack is not on the significance of eternal forms for knowledge, but upon the separation of the form or essence of a thing in another realm from the actual existent thing. Any thing, any individual particular substance, a frog or dog or man, is a unity, says Aristotle; it is not something that exists apart from its own essence. A thing, says Aristotle, is a unity of form and matter. The form of a thing is immanent in it, it is the universal and eternal form or essence which the thing shares with all other things of the same type or species, e.g., with all other frogs or dogs or men. Matter is the physical stuff of the particular substance, which is given shape by the substance’s form. Matter and form are the inseparable aspects of every individual substance.
With his introduction of the inseparable principles of matter and form, Aristotle is able to overcome Plato’s dualism of the intelligible and sensible worlds. For Aristotle, intelligible form and sensible matter–the universal and the particular–are united in individual things. Every individual thing consists of formed matter. The form is the purpose or end which the matter serves: the oak tree is the purpose or end which the matter of the acorn serves.”
(Lavine, From Socrates to Sartre, 70-71)