A tautology's truth is certain, a proposition's possible, a contradiction's impossible. (Certain, possible, impossible: here we have the first indication of the scale that we need in the theory of probability.)

Summary

This quote explains the certainty and possibilities associated with different logical statements. It states that a tautology, which is a statement that is always true, is certain. A proposition, which is a statement that can be true or false, is described as possible. On the other hand, a contradiction, which is a statement that cannot be true, is impossible. These terms also hint at the scale necessary when working with probability theory, as certainty, possibility, and impossibility play crucial roles in understanding and assigning probabilities to events.

Topics