To consider the matter aright, reason is nothing but a wonderful and unintelligible instinct in our souls, which carries us along a certain train of ideas, and endows them with particular qualities, according to their particular situations and relations. This instinct, 'tis true, arises from past observation and experience; but can anyone give the ultimate reason, why past experience and observation produces such an effect, any more than why nature alone should produce it?
David HumeReason, in a strict sense, as meaning the judgment of truth and falsehood, can never, of itself, be any motive to the will, and can have no influence but so far as it touches some passion or affection. Abstract relations of ideas are the object of curiosity, not of volition. And matters of fact, where they are neither good nor evil, where they neither excite desire nor aversion, are totally indifferent, and whether known or unknown, whether mistaken or rightly apprehended, cannot be regarded as any motive to action.
David Hume