(ひゅーむのふぉーく hume's fork)
All the objects of human reason or enquiry may naturally be divided into two kinds, to wit, Relations of Ideas, and Matters of Fact. Of the first kind are the sciences of Geometry, Algebra, and Arithmetic; and in short, every affirmation, which is either intuitively or demonstratively certain. That the square of the hypothenuse is equal to the squares of the two sides, is a proposition, which expresses a relation between these figures. That three times five is equal to the half of thirty, expresses a relation between these numbers. Propositions of this kind are discoverable by the mere operation of thought, without dependence on what is any where existent in the universe. Though there never were a circle or triangle in nature, the truths, demonstrated by Euclid, would for ever retain their certainty and evidence.
Matters of fact, which are the second objects of human reason, are not ascertained in the same manner; nor is our evidence of their truth, however great, of a like nature with the foregoing. The contrary of every matter of fact is still possible; because it can never imply a contradiction, and is conceived by the mind with the same facility and distinctness, as if ever so conformable to reality. That the sun will not rise to-morrowis no less intelligible a proposition, and implies no more contradiction, than the affirmation, that it will rise. We should in vain, therefore, attempt to demonstrate its falsehood. Were it demonstratively false, it would imply a contradiction, and could never be distinctly conceived by the mind.
---Hume
ヒュームに帰せられる、 事実についての命題と観念(概念)の関係についての命題との区別のこと。 総合判断と分析判断 の区別を参照せよ。
気をつけなければならないのは、 自分が何かを主張するとき、 ヒュームが区別したどちらの意味でその命題を用いているのかに気をつけなければ ならないということである。 とくに、 事実を主張しているつもりで実は「定義によって真」 なことを主張している場合があるので注意が必要である。 これについてはまた適切な例が浮かんだら書く。
28/Jan/2004
上の引用は以下の著作から。