Logic's a bitch

The whole weekend I was in TAM. It was an interesting experience and I'll write more about it, but I want to tackle another subject. Last night I met someone there (well, actually in the after drinking) who told me an anecdote on logic. Logic is difficult. Not the algebraic formalism. That part, even though it is always the part which is taught at school at University again and again, is the easy part. The difficulty in logic is mapping the concepts that we are trying to express and interpret the results. Which is never given so much time. Natural language is particularly ill suited for expressing logical concepts. That is why we use logic in the first place.

Because of this gap between what we are thinking and what we can express in a formal language it is easy to fall into fallacies of different kinds. In this mapping there is denotation v.s. connotation, context dependency and all sorts of irregularities in the way natural languages work. And this if we have the problem stated in natural language which may actually be our goal.

Well, the anecdote. Apparently when he was in Mexico there were this guys giving out cards with prostitutes photos and phones. One of them had written on it: "If I am not her, I leave"

by the photo. I may not remember what he said right (I was a tad drunk at the moment). He then made some comment about symbolic logic and told us how he got all the cards. The real question is: Is the statement logically wrong?. If the statement is what I remember, then the discussion is void, but if it is, I think it is right.

In the sentence "I" denotes the real prostitute who actually wrote the ad and who goes to the place. "Her", means the photo of the woman printed in the card. If both are not the same, then the woman going to the house which is I, would leave.

If the statement was "If I am not her, she leaves", would actually have a contradiction embedded, because she is not there as the whole context of the card points to the "real" woman being the one in the first person. From the context, the woman of the photo may not even exist as a real person.

In any case, this simple statement is quite complex to analyze.

Logic is difficult.