Henri Poincare Logic Quotations

It is with logic that one proves; it is with intuition that one invents.

A sane mind should not be guilty of a logical fallacy, yet there are very fine minds incapable of following mathematical demonstrations.

What is a good definition? For the philosopher or the scientist, it is a definition which applies to all the objects to be defined, and applies only to them; it is that which satisfies the rules of logic. But in education it is not that; it is one that can be understood by the pupils.

Pure logic could never lead us to anything but tautologies; it can create nothing new; not from it alone can any science issue.

There are no solved problems; there are only problems that are more or less solved.

It is by logic that we prove, but by intuition that we discover. To know how to criticize is good, to know how to create is better.