The doctrine of Forms or Ideas is the central to Plato’s entire philosophical thought. By this unique contribution, Plato made a real distinction between the visible world and the intelligible world, between appearance and reality. For Plato, the Forms or Ideas are changeless, eternal and non-material essences of the visible objects. So, the visible objects are merely poor copies of the Forms. For instance, a beautiful person is a copy of Beauty. It indicates that a person shares more or less an Idea of Beauty.
Moreover, this doctrine represents a serious attempt to explain the nature of existence, because we have certain kinds of experiences which raise the question about existence for us. For example, we make judgments about things and behavior, saying about a thing that it is beautiful and about an act that it is good. This implies that there is somewhere a standard of Beauty and Good, separate from the person and his act about which we are making judgments. And compared with the visible things, which come and go general and perish, Ideas or Forms seem timeless. They have more being than things. Plato, therefore, concludes that the real world is not the visible world, rather the intelligible world. He insists that the intelligible world is most real, because it consists of the eternal Forms.
There are at last five questions that one might ask about the Forms, such as:
1- What are the Forms?
2- Where do the Forms exist?
3- What is the relation of Forms to things?
4-What is the relation of Forms to each other?
5- How do we know the Forms?
What are the Forms?
Plato’s answer to this question is that Forms are eternal patters of the visible objects and the objects are only copies of these Forms. Thus, a beautiful object is a copy of Beauty. In the Symposium, Plato suggests that we normally understand Beauty first of all in a particular object or person. But having discovered beauty in this limited form, we soon perceive that the beauty of one form is akin to another. So, we move from the beauty of particular body to the recognition that beauty in every Form is one and the same. The effect of the discovery is to move from the beautiful physical object to the concept of beauty. It has objective reality. Things become beautiful but Beauty always is Form which everything else derives its beauty. And, Beauty has a separate existence from these changing things.
Where do the forms exist ?
Plato’s suggestive language regarding the existence of Forms is that they are separate from and apart from the things we see. The forms or Ideas have an independence from the things that perish. Though we are told that the forms have no dimension but the question of their location comes up as a consequence of Plato’s language, implying that Forms, being something must be some place in space. It may be that nothing more can be said about their location than the fact that the Forms have an independent existence. But there are two additional ways in which these is emphasized by Plato. For one way, he says that the soul of men was squinted with the Forms, before it was united with the body. Secondly God used the Forms in creating particular things in the process of creation. If suggests that the forms had an existence prior to their images fashioned by God in things. So, the Forms seem to have originally existed in the mind of God.
What is the relation of Forms to things?
Forms can be related to things in three ways, which may be three ways of saying the same thing. First, the Forms are the cause of the essence of a thing. Next anything may be said to participate in a Form. And finally, a thing may be said to imitate or copy a Form. In each case Plato implies that although the Form is separate from a thing, still every concrete or actual thing in some way owes its existence to a Form, in some degree participates in the perfect model of the class of which it is a member, and is in some measure an imitation or copy of the Form.
What is the Relation of Forms to each other?
Plato implies that Forms are related to each other as genus and species. There are the Forms of animal and such sub-classes of Forms as Man and Horse .The Form Animal seems to be present also in the Form Horse, so that one Form partakes of the other. There is therefore a hierarchy of reality, of which the visible world is only a reflection. The lower one comes in this hierarchy of Forms, the closer he comes to visible things and therefore the less. And there is also the power of desire, love which lead men step by step from the beautiful object to the beautiful thought and then to the very essence of Beauty itself. No double there are many points in this theory that deserve fuller explanation.
How do we know the Forms?
According to Plato, we can know the Forms through reminiscence. To him, humans are acquainted with the Forms in their per-existence of the soul. Now, they can recall the Forms when they see the visible things.
Thus, Plato’s theory of Forms is central to his philosophy. It was also very influential upon the subsequent philosophers. Plato’s own moral and political theories are also derived from this theory of Forms.