The owner of a pet shop is a retired mathematician. He never lies, and he makes very precise statements. He tells a customer the parrot in the cage is extremely intelligent - in fact, "this bird will repeat every word he hears." The customer, impressed, buys the parrot. In a few days, the outraged customer returns with the parrot, saying, "I spoke to him for hours every day, but this stupid bird has not repeated a single word I said." Nevertheless, the pet shop proprietor did not lie. Is this possible?
There are a number of solutions to this problem. Here are a few:
The bird is deaf (in physical terms, there is no initial condition). This is the most obvious solution. The bird will repeat every word he hears, but he cannot hear anything.
Since the proprietor did not say when the bird will repeat what he hears, an other answer is that the bird will repeat every word - in a few years. (The mathematician's solution has been translated along the t axis.)
The highly intelligent bird may well have ignored his new owner, who was an extremely boring conversationalist. After all, would an intelligent person speak to the parrot just to have it repeat the words?
The customer may be lying. (His wife found out how much the bird cost and forced him to return it.)
There are many solutions even more ridiculous than these. The situation arises from application of rigorous mathematical language to everyday usage, which is imprecise. The use of mathematical rigor in common communication would be maddeningly inconvenient. In everyday language, much is tacitly implied. The scientist lives between these extremes, and needs to check all definitions and descriptions to be certain of his or her understanding.
Language of Mathematics, Language of Science and Plain Language
Copyright © 1996-2009 Alexander Bogomolny
