A mental attitude of acceptance or assent toward a proposition without the full intellectual knowledge required to guarantee its truth. Believing is either an intellectual judgement or, as the 18th century Scottish skeptic David Hume maintained, "a special sort of feeling with overtones that differ from those of disbelief." Beliefs have been distinguished according to their degree of certainty: a surmise or suspicion, an opinion, or a conviction. Belief becomes knowledge only when the truth of a proposition becomes evident to the believer. Belief in someone or something is basically different from belief that a proposition is true.