Plato's Theory Of Forms

 Plato's Theory of Forms is an epistemological response to the nature of reality. This means Plato attempts to answer the question 'what is true reality?'. The idea is that every object in the world we see, is a less-perfect copy of an ideal object found in a world Plato calls the 'Realm of the Forms'. Our souls have visited the Realm of the Forms before entering our bodies and so this is how we can identify common objects such as a 'chair' or a 'cat'.

Plato puts forward the 'cave analogy' to emphasise his theory of Forms. In this, the 'cave' represents the world we live in (a world Plato calls 'world of appearances'), and prisoners that are chained up represent trapped humanity. The prisoners are facing a wall where they can see shadows of objects they believe to be real, and in order to truely understand the shadows one has to escape and make the journey out of the cave. When a prisoner leaves the cave they will see true reality in the form of the outside world and so have sought true knowledge. This supports Plato's Theory of Forms because it shows that an escaped prisoner can understand his reality, much like we as individuals can understand our world as long as we continue to pursue philosophical knowledge.

Arguments for Existence of Forms

Plato sometimes writes as if he takes the existence of Forms for granted, as a matter of faith. But sometimes he offers arguments for them. Each argument is connected to a function Plato has in mind for Forms to play. Some of these “reasons” for believing in Forms don’t really add up to arguments, but some do. Plato, in any event, was not very systematic about his arguments.

1 Forms are objects corresponding to Socratic definitions.

A Form is supposed to provide an objective basis for moral concepts. A definition is correct just in case it accurately describes a Form. The definition of Justice, e.g., is that statement which correctly tells us What Justice Is.

2 Forms are objects of recollection.

The knowledge we get when we are in possession of a Socratic definition is a priori, not empirical. So Forms are the entities for such a priori (= recollectible) truths to be about.

3 Arguments of Imperfection.

Forms are the real entities to which the objects of our sensory experience (approximately) correspond. We make judgments about such properties as equal, circular, square, etc., even though we have never actually experienced any of them in perception. Forms are the entities that perfectly embody these characteristics we have in mind even though we have never experienced them perceptually.

4 Argument from knowledge (“from the sciences”).

What is our knowledge “about”? When we know something, what is our knowledge knowledge of? Plato supposes that there is a class of stable, permanent, and unchanging objects that warrant our knowledge claims.

5 One Over Many

 A famous passage in the Republic (596a) suggests a semantic role for the Forms (“there is one Form for each set of many things to which we give the same name”). That is, when you use the word ‘just’ and I use the word ‘just’, what makes it one and the same thing that we’re talking about? Plato’s answer is: the Form of Justice, the “one over the many.”

    Plato believes that there is a non-conventionalist answer to questions of meaning: there is some one thing that is referred to by ‘just’ whenever it is used. Hence, when you talk about justice and I talk about justice, we are talking about the same thing. We belong to the same world, not each of us in his own private world. If we disagree in what we apply the term ‘just’ to, we cannot both be right.

    The last three of these arguments are especially important. They correspond to three of the problems the Forms are supposed to solve. We’ll look at the first of these in the Phaedo, and at the others later.