Charles Sanders Peirce

“To reason is to generalize.”

“Logic is the art of drawing inferences.”

“The opinion which is fated to be ultimately agreed to by all who investigate, is what we mean by the truth.”

“We do not really think, we are barely conscious, until we are forced to think, and we are not forced to think unless we are in a state of doubt.”

“A fallacy is an argument that seems to be correct, but is not.”

“The entire intellectual purport of any symbol consists in the total of all general modes of rational conduct which would ensue upon the acceptance of the symbol.”

“The scientific man is not in the least wedded to his conclusions. He is leaning backwards, in the attitude of doubt.”

“A man must be outright silly to have the hunters' instinct of the conclusion.”

“Let us not block the way of inquiry.”

“Feeling is a quality of immediate consciousness.”

“All the evolution we know of proceeds from the vague to the definite.”

“A sign is something by knowing which we know something more.”

“Thought is not necessarily connected with a brain.”

“We think only in signs.”

“The first, and in one sense the sole, rule of reason is, that in order to learn you must desire to learn.”

“The very first lesson that we have a right to demand that logic shall teach us is, how to make our ideas clear.”

“The elements of every concept enter into logical thought at the gate of perception and make their exit at the gate of purposive action.”

“I am, as far as I know, a pioneer, or rather a backwoodsman, in the work of clearing and opening up what I call semiotic.”

“Genuine doubt is the first step toward knowledge.”

“The soul is a sign.”