Theory of forms

The Theory of Forms typically refers to Plato's belief that the material world as it seems to us is not the real world, but only a shadow of the real world. Plato spoke of forms (sometimes capitalized in translations: The Forms) in formulating his solution to the problem of universals. The forms, according to Plato, are roughly speaking archetypes or abstract representations of the many types and properties (that is, of universals) of things we see all around us.

Forms
Form and idea are terms used to translate the Greek word (eidos). According to Plato's view, there is a form for every object or quality in reality: forms of dogs, human beings, mountains, colors, courage, love, and goodness. Indeed, for Plato, "god" is identical to the Form of the Good. Forms exist in a "Platonic heaven," and when people die (or, as by contemplation, become detached from the material world), their souls achieve reunion with the forms. Plato makes it clear that souls originate in this "Platonic heaven" and have recollection of it even in life.

The objects that participate in a Form are called particulars. Forms are not the cause of a particular. If the Form cannot exist, the object under that Form--the particular--cannot exist. The Forms constitute the possibility of things, they are the necessary condition for a particular to exist.

These Forms represent the essence of various objects: they are that without which, a thing would not be the kind of thing it is. For example, there are countless tables in the world but the Form of tableness is at the core, it is the essence, of all of them. Plato held that the World of Forms was separate from our own world and also the true basis of reality. Forms are, in this way, the most pure of all things. Furthermore, Plato believed that true knowledge/intelligence was the ability to grasp the world of Forms with one's mind.

A Form is aspatial (outside the world) and atemporal (outside time). Atemporal, that is, it does not exist within any time period. It did not start, there is no duration in time, and it will not end. It is not eternal in the sense of existing forever. It exists outside time. Forms are aspatial in that they have no spatial dimensions, and thus no orientation in space. They are non-physical, but they are not in the mind. Forms are extra-mental.

A form is an objective "blueprint" of perfection. The Forms are perfect themselves because they are unchanging. For example, say we have a triangle drawn on a blackboard. A triangle is a polygon with 3 sides. The triangle as it is on the blackboard is far from perfect. However, it is only the intelligibility of the Form "triangle" that allows us to know the drawing on the chalkboard is a triangle.

Several of Plato's dialogues make use of the Forms, including Plato's Parmenides, which outline several of Plato's own objections to his Theory of Forms.

Evidence of Forms
The idea of Forms was explained or alluded to in several Platonic Dialogues, most notably the Republic. Various forms of evidence are given for Plato's belief in Forms.


 * The ethical argument. Heraclitus argues that everything is in motion, thus giving rise to ethical relativism.  However, by arguing that only our false material world is in motion, and that the world of forms is static, Plato could save moral universals by postulating the Form of the Good.


 * The argument from human perception. We call both the sky and blue jeans by the same color:  Blue.  However, clearly a pair of jeans and the sky are not the same color.  Thus, we somehow have an idea of the basic form Blueness which we can relate to various objects.


 * The argument from Perfection. No one has ever seen a perfect circle, nor a perfectly straight line, yet everyone knows what a circle and a straight line are.  Again, Plato contends that via reincarnation we can have a recollection of the perfect forms. It was during extreme physical stress (i.e. birth) that we forget the Forms. If during life you recollect all of the Forms and learn to love the Forms, you can escape the circle of reincarnation.

The debate about forms would become among the most important discussions in the Middle Ages, though the notion of forms as being otherworldly was typically rejected. Aristotle's theory about forms (called Hylomorphism) is noteworthy.

Criticisms of Platonic Forms
Plato offered his own criticisms of the theory of forms in his dialogue Parmenides. Among these is the famous Third Man Argument. It is debated whether Plato saw these criticisms off as conclusively disproving the theory of forms. Of note, he excludes forms from his last work, The Laws.

Aristotle claimed that the human mind naturally thought in the abstract and that the fact that a person could separate forms from objects in their own mind didn't necessarily mean that forms existed separately from objects. Aristotle calls the theory of forms "idle chatter" in Posterior Analytics.

Aristotle's analysis of nature proposed a formal cause in addition to the material cause, efficient cause, and final cause.