rationalism

Rationalism is the conviction that the surest road to knowledge runs through reason — through careful thinking — and not through the senses alone. The eyes and ears bring in raw material, but the mind, a rationalist says, is what truly weighs, orders, and grasps the truth. Picture a detective who solves the case not by gathering one more clue, but by sitting quietly and reasoning out what must have happened: that armchair is the rationalist's favorite seat.

Its boldest claim is that some truths can be known by thought alone, with no need to go and look. That nothing can both exist and not exist at once, that two plus three makes five — you don't run experiments to check these; you simply see, with the inner eye of reason, that they could not be otherwise. The most famous rationalist, René Descartes, doubted everything he possibly could until he hit bedrock: the very act of doubting proved he was thinking, and thinking proved he existed — "I think, therefore I am."

It helps to clear up a common mix-up. Rationalism is not the opposite of emotion, and it doesn't mean ignoring the senses entirely — a rationalist happily uses observation. The real contrast is with empiricism, the rival view that experience is the only true source of knowledge. Rationalists answer: experience alone can never give us certainty, so reason must supply the rest.