Charles Sanders Peirce Quotes

I can believe things that are true and things that aren't true and I can believe things where nobody knows if they're true or not.

Realism is punishing. Probabilistic skepticism is worse.

Everyone who observes himself doubting observes a truth, and about that which he observes he is certain; therefore he is certain about a truth. Everyone therefore who doubts whether truth exists has in himself a truth on which not to doubt.... Hence one who can doubt at all ought not to doubt the existence of truth.

Where doubt there truth is - 'tis her shadow.

It is not by believing but by doubting that one can attain to the truth, which is ever changing form and condition.

What can we say with certainty?

If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty.

Dogmatism and skepticism are both, in a sense, absolute philosophies; one is certain of knowing, the other of not knowing. What philosophy should dissipate is certainty, whether of knowledge or ignorance.

Doubt is not an agreeable condition, but certainty is an absurd one.

We'd all like to be certain of what we know, but I think the most important question is to ask yourself do you really know what you know?

Pain is truth; all else is subject to doubt.

The first lesson about trusting your senses is: don't. Just because you believe something to be true, just because you know it's true, that doesn't mean it is true.

I don't believe anything till I have seen the proof. For anything without proof, I think we should believe the theory that gives us peace. It doesn't matter whether the theory is true or not.

Except in pure mathematics, nothing is known for certain (although much is certainly false).

If I wanted to doubt, then I could doubt endlessly, but at some point a person has to stop questioning and act, and at that point you have to trust something to be true. You have to act as if something is true, and so you choose the thing you have the most reason to believe in, you have to live in the world that you have the most hope in.

... I distrust manifest knowledge.

I might as well doubt of my own being, as of the being of those things I actually see and feel.

I believe in everything - a little bit.

You do not believe, you only believe that you believe.

I've gone through most of my life not believing anything. Either I know or I don't know, or I think.

I think maybe it is better to believe than not to believe. But I couldn't tell you why.

Is there any knowledge in the world which is so certain that no reasonable man could doubt it?

Il n'est pas certain que tout soit incertain. (Translation: It is not certain that everything is uncertain.)

Never believe what you cannot doubt.