Effort supposes resistance.
Every new concept first comes to the mind in a judgment.
The universe ought to be presumed too vast to have any character.
It is... easy to be certain. One has only to be sufficiently vague.
We do not really think, we are barely conscious, until something goes wrong.
By an object, I mean anything that we can think, i.e. anything we can talk about.
Mathematics is purely hypothetical: it produces nothing but conditional propositions.
The definition of definition is at bottom just what the maxim of pragmatism expresses.
There is a kink in my damned brain that prevents me from thinking as other people think.
The one primary and fundamental law of mental action consists in a tendency to generalisation.
Every man is fully satisfied that there is such a thing as truth, or he would not ask any question.
Another characteristic of mathematical thought is that it can have no success where it cannot generalize.
Mathematics is distinguished from all other sciences except only ethics, in standing in no need of ethics.
Unless man have a natural bent in accordance with nature's, he has no chance of understanding nature at all.
Bad reasoning as well as good reasoning is possible; and this fact is the foundation of the practical side of logic.
Few persons care to study logic, because everybody conceives himself to be proficient enough in the art of reasoning already.
If man were immortal he could be perfectly sure of seeing the day when everything in which he had trusted should betray his trust.
All the progress we have made in philosophy ... is the result of that methodical skepticism which is the element of human freedom.
One of the most marked features about the law of mind is that it makes time to have a definite direction of flow from past to future.
The one [the logician] studies the science of drawing conclusions, the other [the mathematician] the science which draws necessary conclusions.