The theory of truth is a series of truisms.

"What is truth?" said jesting Pilate, and would not stay for an answer. Pilate was in advance of his time. For "truth" itself is an abstract noun, a camel, that is, of a logical construction, which cannot get past the eye even of a grammarian. We approach it cap and categories in hand: we ask ourselves whether Truth is a substance (the Truth, the Body of Knowledge), or a quality (something like the colour red, inhering in truths), or a relation ("correspondence"). But philosophers should take something more nearly their own size to strain at. What needs discussing rather is the use, or certain uses, of the word "true." In vino, possibly, "veritas," but in a sober symposium "verum."

Going back into the history of a word, very often into Latin, we come back pretty commonly to pictures or models of how things happen or are done.

Next, 'real' is what we may call a trouser-word. It is usually thought, and I dare say usually rightly thought, that what one might call the affirmative use of a term is basic--that, to understand 'x,' we need to know what it is to be x, or to be an x, and that knowing this apprises us of what it is not to be x, not to be an x. But with 'real' (as we briefly noted earlier) it is the negative use that wears the trousers.

There is no one kind of thing that we 'perceive' but many different kinds, the number being reducible if at all by scientific investigation and not by philosophy: pens are in many ways though not in all ways unlike rainbows, which are in many ways though not in all ways unlike after-images, which in turn are in many ways but not in all ways unlike pictures on the cinema-screen--and so on.

Usually it is uses of words, not words in themselves, that are properly called vague.

After all we speak of people 'taking refuge' in vagueness -the more precise you are, in general the more likely you are to be wrong, whereas you stand a good chance of not being wrong if you make it vague enough.