To begin with, we must radically disabuse our minds of the idea that thinking starts from certainty. Even the self-evident and self-confident 'intuitions' that impress the uncritical so much with their claim to infallibility are really the results of antecedent doubts and ponderings, and would never be enunciated unless there were thought to be a dispute about them. In real life thought starts from perplexities, from situations in which, as Professor Dewey says, beliefs have to be 'reconstructed, ' and it aims at setting doubts at rest. It is psychologically impossible for a rational mind to assert what it knows to be true, and supposes everyone else to admit the truth of.