last revised September 8th, 2004.This week I want to give you a feel for the history of our topic. It cannot pretend to deal seriously with any of the persons it mentions, but you need to be aware of what has happened in the tradition.
For some lengthier discussion of Plato you can check my lecture from the Greek Philosophy course.
Plato's work presents us with a view of the nature of reality that is very far from ordinary assumptions. (I do not say that this view is Plato's at any point in his career; for now we are only concerned with views that are associated with Plato's name.) Ordinary things are beautiful, ordinary actions are courageous. If asked what beauty or courage are, ordinary people might be content to point to such ordinary things and occurrences. But Plato suggests a different answer: in addition to, separate from, these ordinary things and occurrences there are Forms of beauty or courage. These we can grasp with our minds (our senses stop at the ordinary things and occurrences) and it is somehow because of them that the ordinary things or occurrences are what they are. These Forms are pre-eminently real, pre-eminently what it is to be beautiful or courageous.
If you try to say what courage is, and you say it is a matter of actions having feature F, then Plato argues that he can find an action that is F but isn't courageous. If you say that beauty is a matter of being like object X, then Plato suggests that he can find a context in which we would judge object X not-beautiful. The only thing that is F without qualification is the Form of F.
Elsewhere, Plato floats the idea that before this life we were acquainted with the Forms, and that what we regard as learning in this life is a matter of remembering what we were then aware of.
Elsewhere again, Plato subjects these ideas to intense criticism, most famously with the "Third Man" argument. If you say that the Fs are all F because they relate somehow to the Form of F, then consider the group made up of F things and the Form of F. This group is all F, so it must be so by relating to yet another Form of F. And so you are started upon an endless reiteration of Forms of F.
Much can be said about the precise details of Plato's ideas here. For now, our concern is simply to note that Platonism amounts to a vew that there are some sorts of entities very different from the denizens of space-time, and that we have good reasons to believe in their existence.
In this very attenuated sense, Platonism remains very much a viable option for philosophers. Especially in the context of mathematics, Platonism is almost the common-sensical view - however remote it might seem from other common sense. (See the paper by Linsky and Zalta on your diskette, and Balaguer's SEP article.)
For some lengthier discussion of Aristotle you can check my lecture from the Greek Philosophy course.
Aristotle can be seen as reacting negatively to Plato's apparently other-worldly account of what makes this world the way it is. In what is usually thought a comparatively early work, the Categories, he is insistent that the fundamental things that exist are particular individuals, this man, that horse, etc. These he calls primary substances. The kinds to which they belong he calls secondary substances. Substances can exhibit various properties, and indeed he offers a listing of these different categories: quantity, quality, relation, etc. But all these are seen as dependent on substances: you need something, a substance, before you can have red, or 2 kilograms, or in the market-place.
Elsewhere, Aristotle complicated his story to account for the coming-into-being and going-out-of-being of primary substances. Ordinary change in a substance involves the same substance having contrary properties at different times - now I am hot, later I am cool. So, for Aristotle, change of substance requires something to remain unchanged, what he calls the matter. The same matter starts off with one form and switches to another. The original primary substances are now construed as unified composites of form and matter.
In Aristotle's later reflections, these ideas get taken much further, but he remains convinced that we do not need anything like Platonic Forms to grasp the world we live in or even the mathematics we use in doing so. Things get more complicated when we rise to general cosmology, since Aristotle does there postulate an Unmoved Mover that is immaterial, something that "moves without being moved, being eternal, substance and actuality" (1072a24-6).
With the resurgence of Aristotelian philosophy in the mediaeval West, Aristotle's framework provided for several centuries the basic vocabulary for philosophizing and for explicating, as far as is possible, the mysteries associated with the Christian faith. Even when it was rejected, it still provided much of the terminology and the key issues, e.g. the association of substance with independent existence, that had such powerful effects on Spinoza's thinking.
© Ed Brandon, 2004.
last revised September 8th, 2004.
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