Laws of logic

Japanese: 論理法則 - ろんりほうそく

The traditional understanding of logical laws is that they are the most general and fundamental laws that human thought must follow. The three principles of identity, contradiction, and the excluded middle have traditionally been cited as the fundamental principles of logic that represent logical laws. The law of identity is expressed as " A is A ," the law of contradiction as " A and not non- A ," and the law of the excluded middle as " A or not- A ." From the standpoint of modern logic, we can symbolize these fundamental principles. If we can understand A as a proposition (descriptive sentence), then these are expressed as " A ⇒ A ," "~( A ∧~ A )," and "A ∨~ A " (meaning ⇒: then, ~: not, ∧: and, ∨: or).

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

人間の思考が従うべきもっとも一般的かつ基本的な法則，というのが論理法則の伝統的な理解である。そして論理法則を代表する論理学の根本原理として，同一律，矛盾律，排中律の三原則が挙げられるのが通例であった。同一律は〈AはAである〉と，矛盾律は〈Aかつ非Aでない〉と，排中律は〈Aまたは非A〉と表現される法則である。現代論理学の立場からわれわれはこれらの根本原則を記号化することができる。仮にAを命題(記述文)と理解してよいなら，それぞれ，〈A⇒A〉〈～(A∧～A)〉〈A∨～A〉(⇒：ならば，～：ない，∧：かつ，∨：または，の意)。

出典　株式会社平凡社世界大百科事典第２版について　情報

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