Chapter 15 - The Theory of Ideas

(Originally written June 8, 2016 in Book 26)

History of Western Philosophy
Bertrand Russell

Chapter XV - The Theory of Ideas

Plato asks what is a philosopher and answers, "a lover of wisdom", not just an intellectual curiosity, but a man who loves the vision of truth.

The vision of truth is the demarcation of opinion and knowledge. The art lover may love beautiful things, movies, paintings, music, etc. But, the philosopher loves beauty itself. The lover of beautiful things has opinions; the philosopher has knowledge.

Plato held that knowledge was infallible, but opinion can be false. Knowledge is of things that are, that is to say, to have knowledge is to have knowledge of something. But particular things have contradictory existences and thus are suited for opinion only. A particular thing is simultaneously beautiful and ugly. That particular thing is somewhere between being and non-being. There is no knowledge of a particular, only of the eternal. "Thus we arrive at the conclusion that opinion is of the world presented to the senses, whereas knowledge is of a supersensible eternal world" (Russell, 121).

Plato arrives at the dichotomy of opinion and knowledge by combining Parmenides' notion of what is, is and what is not, is not (nothing does not exist) with Heraclitus' notion of we are and we are not to. Combining the two we necessarily have particular items that both are and both are not, to which knowledge cannot be applied and necessitates opinion. But since knowledge exists and knowledge demands that it must know some 'thing', some 'thing' must exist.

The 'thing' of which knowledge is capable of cannot be a particular thing from a logical standpoint. The word, "cat" for instance can be used to describe a number of particular cats and the meaning of the word cat preexists and retains meaning beyond any particular cat's existence. "If the word 'cat' means anything, it means something which is not this or that cat, but some kind of universal cattyness" (Russell, 121). This is the logical part of Plato's argument for his theory of ideas or forms.

There is also a metaphysical part to his theory. The metaphysical part demands the word 'cat' to mean the ideal cat. This ideal cat is created by God and is unique. All particular cats take part in the nature of the ideal cat imperfectly. Because the particulars take part imperfectly there can be numerous. The eternal cat is what we can have knowledge of. The particular cats we have opinions of. The eternal cat is real. Particular cats merely have appearance because they are a representation of the real cat.

The philosopher is only concerned with the real things. He is concerned with the things that God has made, which are universal. He isn't concerned with the particulars, which are mere copies.

Plato uses the analogy of the cave to explain the difference between knowledge acquired through reason and understanding via sense perception. He likens the acquisition of knowledge to seeing a thing in the light of day whereas when we use sense perception we are akin to viewing something in the twighlight hours and thus, our vision is cloudy and confused.

Plato likens the philosopher to a group of men bound in a cave who see only the shadows of themselves and objects on the cave wall. The philoospher is the man who escapes and sees the real objects (by leaving the cave). If he truly is a philosopher and fit to be a guardian, he will be compelled to teach the others still believing in the shadows to be the real objects erroneously. But this will be a difficult task for the philosopher as he, having viewed sunlight, will have a harder time distinguishing the shadows in the darkness of the cave than the others who have not seen the sun.

Plato has an interesting notion of the good. He claims science and truth are like the good, but the good is higher. To Plato the reality is the good, the appearance is like the good.

Plato marks the beginning of serious intellectual discourse on universals and the problem of universals.