The "Four causes" refers to an influential principle in Aristotelian thought whereby explanations of change or movement are classified into four fundamental types of answer to the question "why?". Aristotle wrote that "we do not have knowledge of a thing until we have grasped its why, that is to say, its cause." While there are cases where identifying a "cause" is difficult, or in which "causes" might merge, Aristotle was convinced that his four "causes" provided an analytical scheme of general applicability. Aitia, from Greek αἰτία was the word that Aristotle used to refer to the causal explanation that has traditionally been translated as "cause", but this specialized, technical, philosophical usage of the word "cause" does not correspond to its most usual uses in everyday language. The translation of Aristotle's αἰτία that is nearest to current ordinary language is "explanation". In this article, the peculiar philosophical usage of the word...