I was mulling over this need to be middle class when I opened the next thing in my post, a book on logic from Amazon. I started reading it at once -- I think I'll enjoy it more once it gets onto the Maths and stops trying to do "real world" logical analysis of things people say at after-dinner speeches. Here's one of the little exercises at the end of the first chapter, which you have to inspect for internal consistency:
Walter joined the friendly club two years ago, and has been one of its most loyal members ever since. Last year he paid for the holidays of precisely those club members who didn't pay for their own holidays.
Whilst of course I'm familiar with that particular "he shaved others, himself he could not shave" paradox, I was bemused to read in the answers at the back that this statement is inconsistent because of the question of who paid for Walter's holiday. I had just assumed that Walter would avoid this excessive amount of self-definition by not going on holiday, especially if he has to work hard to pay for the holidays of others. Since when has it been assumed that everyone goes on holiday? Is that now an intrinsic part of human existence? The fact that I can't read something like this without being really annoyed and even stopping to blog about it makes me worry that I am just over-educated, and that the excellence of the teaching in my first degree has spoiled me for normal just-let-it-go life. But surely if one's allowed to pick pedantic holes in anything it's a textbook on logic.
Quite right, not good enough, insufficient definition of terms at the outset. If you're in the market for another logic textbook at any point, I can thoroughly recommend 'Logic' by Paul Tomassi, which is very clear and also entertaining.
ReplyDeleteThanks for the recommendation, I might try that one if this one continues to be irritating. I want most to learn about formal logic. I've been reading Roger Penrose's The Emperor's New Mind on and off for ages now, and I was intrigued by a reference to people who don't accept that not not p is the same as p. I find this a very appealing idea.
ReplyDeleteThe other problem I have with Wilfrid Hodges' Logic book is that he's arguing that logic is intrinsic to human nature, and attractive to us. It's a flaw in me, not in his writing, that every example he gives of illogic sounds to me like the starting point of a short story. Here's one of the statements which he has as an example of internal logical consistency within the statement even though there are other things we know which make it unlikely:
"The surface of the earth is flat (apart from mountains, oceans and other relatively small bumps and dips). When people think they have sailed around the earth, all they have really done is to set out from one place and finish up in another place exactly like the one they started from, but several thousand miles away."
That's clearly a short story by Italo Calvino or maybe Umberto Eco, or if you substitute time for space it sounds like the sort of thing people say in modern physics.