A Logic of Vision

1 Introduction Our mistake lies in supposing that things present themselves as they really are, names as they are written, people as photography and psychology give an unalterable picture of them. But in reality this is not at all what we ordinarily perceive. We see, we hear, we conceive the world in a lopsided fashion. Is there a logic of perception? And if there is, how is it related to the semantics and pragmatics of perception reports? These are the main questions we will address in the present essay. Inspired by Marr 1982, we shall argue that perception is approximative in many ways, and should hence allow for failure and correction. Consequently, the description of perception should also be retractable. This position has been defended more often, but it still poses many interesting challenges. These are perhaps best exemplified by a passage from Proust's La Fugitive. I opened the Figaro. What a bore! The main article had the same title as the article which I had sent to the paper and which had not appeared. But not merely the same title.. . why, here were several words that were absolutely identical. This was really too bad. I must write and complain. But it wasn't merely a few words, it was the whole thing, and there was my signature.. . It was my article that had appeared at last! But my brain which, even at that period, had begin to show signs of age and to tire easily, continued for a moment longer to reason as though it had not understood that this was my article, like an old man who is obliged to complete a movement that he has begun even if it has become unnecessary, even if an unforeseen obstacle, in the face of which he ought at once to draw back, makes it dangerous. (Penguin Classics ed., p. 579) When looking at the newspaper, the writer must have seen something; but what kind of object did he perceive? Whatever he saw approximated the real newspaper; yet, how do such approximations figure in the description of what he saw? Had 5 Introduction / 6 he been less preoccupied, he would have noticed his article right away. Indeed, we normally do not expect gross misperception; so, what is the precise nature of this expectation? In chapter 3 we try to clarify these issues by means of logico-semantical techniques. The logic …