Plato’s Theory of Forms

Plato (circa 427-347 BC) made contributions to practically every field of human interest and is undoubtedly one of the greatest thinkers of all times. However it is just as well that his political ideas didn’t catch on (except possibly in North Korea); additionally Platonic Realism bogged down biological science until Darwin and Wallace’s time.

Plato was influenced by Pythagoras, Parmenides, Heraclitus and Socrates (Russell (1946)). From Pythagoras he derived the Orphic elements in his philosophy: religion, belief in immortality, other-worldliness, the priestly tone, and all that is involved in the allegory of the cave; mathematics and his intermingling of intellect and mysticism. From Parmenides he derived the view that reality is eternal and timeless and that on logical grounds, all change must be an illusion. From Heraclitus he derived the view that there is nothing permanent in the world of our senses. Combining this with the doctrine of Parmenides led to the conclusion that knowledge is not to be derived from the senses but achieved by intellect – which ties in with Pythagoras. Finally from Socrates came his preoccupation with ethics and his tendency to seek teleological rather than mechanical explanations.

Realism, as opposed to nominalism, refers to the idea that general properties or universals have a mode of existence or form of reality that is independent of the objects that possess them. A universal can be a type, a property or a relation. Types are categories of being, or types of things – e.g. a dog is a type of thing. A specific instance of a type is known as a token, e.g. Rover is a token of a dog. Properties are qualities that describe an object – size, colour, weight, etc, e.g. Rover is a black Labrador. Relations exist between pairs of objects, e.g. if Rover is larger than Gus then there is a relation of is-larger-than between the two dogs. In Platonic Realism universals exist, but only in a broad abstract sense that we cannot come into contact with. The Form is one type of universal.

The Theory of Forms (or Ideas) is referred to in Plato’s Republic and other Socratic Dialogues and follows on from the work of Parmenides and his arguments about the distinction between reality and appearance. The theory states that everything existing in our world is an imperfect copy of a Form (or Idea), which is a perfect object, timeless and unchanging, existing in a higher state of reality; for example there are many types of beds, double, single, four-poster etc but they are only imperfect copies of the Form of the bed, which is the only real bed. Plato frowned upon the idea of painting a bed because the painting would merely be a copy of a copy, and hence even more flawed. The world of Forms contains not only the bed Form but a form for everything else – tables, wristwatches, dogs, horses, etc. Forms are related to particulars (instances of objects and properties) in that a particular is regarded as a copy of its form. For example, a particular apple is said to be a copy of the form of Applehood and the apple’s redness is a copy of the form of Redness. Participation is another relationship between forms and particulars. Particulars are said to participate in the forms, and the forms are said to inhere in the particulars, e.g. redness inheres in an apple. Not all forms are instantiated, but all could be. Forms are capable of being instantiated by many different particulars, which would result in the form having many copies, or inhering many particulars.

Needless to say, the world of the Forms was only accessible to philosophers, a view which justified the Philosopher Kings of the Republic, and casts philosophers in the same role as shamans and priests as people with exclusive access to worlds better than our own, and hence the basis of a ruling elite. That animals have ideal Forms is a view that bogged down biological science for centuries, as it rules out any notion of evolution. (The Republic also advocated such unsavoury practices as eugenics (dressed up as a rigged mating lottery); abolition of the family; censorship of art; and a caste-system based on a “noble lie” of the “myth of metals” (which I suppose is better than a war based on the ignoble lie of the myth of weapons of mass destruction). The Republic seems to have influenced Huxley’s Brave New World, Orwell’s 1984 and the Federation of Heinlein’s Starship Troopers).

The inheritance criticism questions what it means to say that the form of something inheres in a particular or that the particular is a copy of the form. If the form is not spatial, it cannot have a shape, so the particular cannot be the same shape as the form.

Arguments against the inherence criticism claim that a form of something spatial can lack a concrete location and yet have abstract spatial qualities. An apple, for example, can have the same shape as its form. Such arguments typically claim that the relationship between a particular and its form is very intelligible and people apply Platonic theory in everyday life, for example “car”, “aeroplane”, “cat” etc don’t have to refer to specific vehicles, aircraft or cats.

Another criticism of forms relates to the origin of concepts without the benefit of sense-perception. For example, to think of redness-in-general is to think of the form of redness. But how can one have the concept of a form existing in a special realm of the universe, separate from space and time, since such a concept cannot come from sense-perception. Although one can see an apple and its redness, those things merely participate in, or are copies of, the forms. Thus to conceive of a particular apple and its redness is not to conceive of applehood or redness-in-general.

Platonic epistemology, however, addresses such criticism by saying that knowledge is innate and that souls are born with the concepts of the forms. They just have to be reminded of those concepts from back before birth, when they were in close contact with the forms in the Platonic heaven. Plato believed that each soul existed before birth with “The Form of the Good” and a perfect knowledge of everything. Thus, when something is “learned” it is actually just “recalled.”

Plato stated that knowledge is justified true belief, i.e. if we believe something, have a good reason for doing so, and it is in fact true, then the belief is knowledge. For example, if I believe that the King’s Head sells London Pride (because I looked it up in the Good Beer Guide), I get a bus to the pub and see a Fullers sign outside, then I have knowledge that it sells London Pride. This view has been central to epistemological debate ever since Plato’s time.

Plato drew a sharp distinction between knowledge which is certain, and mere opinion which is not certain. Opinions derive from the shifting world of sensation; knowledge derives from the world of timeless forms, or essences. In the Republic, these concepts were illustrated using the metaphor of the sun, the divided line and the allegory of the cave.

Firstly, the metaphor of the sun is used for the source of “intellectual illumination”, which Plato held to be The Form of the Good. The metaphor is about the nature of ultimate reality and how we come to know it. It starts with the eye, which is unusual among the sense organs in that it needs a medium, namely light, in order to operate. The strongest source of light is the sun; with it, we can discern objects clearly. By analogy, we cannot attempt to understand why intelligible objects are as they are and what general categories can be used to understand various particulars around us without reference to forms. “The domain where truth and reality shine resplendent” is Plato’s world of forms, illuminated by the highest of all the forms – the Form of the Good. Since true being resides in the world of the forms, we must direct our intellects there to have knowledge. Otherwise we have mere opinion, i.e that which is not certain.

Secondly, the divided line has two parts that represent the intelligible world and the smaller visible world. Each of those two parts is divided, the segments within the intelligible world represent higher and lower forms and the segments within the visible world represent ordinary visible objects and their shadows, reflections, and other representations. The line segments are unequal and their lengths represent “their comparative clearness and obscurity” and their comparative “reality and truth,” as well as whether we have knowledge or instead mere opinion of the objects. Hence, we are said to have relatively clear knowledge of something that is more real and “true” when we attend to ordinary perceptual objects like rocks and trees; by comparison, if we merely attend to their shadows and reflections, we have relatively obscure opinion of something not quite real.

Finally Plato drew an analogy between human sensation and the shadows that pass along the wall of a cave – the allegory of the cave. Prisoners inside a cave see only the shadows of puppets in front of a fire behind them. If a prisoner is freed, he learns that his previous perception of reality was merely a shadow and that the puppets are more real. If the learner moves outside of the cave, they learn that there are real things of which the puppets are themselves mere imitations, again achieving a greater perception of reality. Thus the mere opinion of viewing only shadows is steadily replaced with knowledge by escape from the cave, into the world of the sun and real objects. Eventually, through intellectualisation, the learner reaches the forms of the objects – i.e. their true reality.

(this article originally appeared on my main blog on 28 January 2008)
© Christopher Seddon 2008, 2014


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