The act of causing; also the act or agency by which an effect is produced.
The relation between two states of affairs when the occurrence of the second is invariably a result of the occurrence of the first. For example, the striking of a dry match invariably causes the match to ignite.
The 18th-century Scottish philosopher David Hume argued that our idea of an effect following necessarily from its cause arises by habit from the repeated observation of causal regularities, such as the striking of dry matches being followed by ignition. Aristotle held that there were four causes of things. The efficient cause of a man, according to Aristotle, is his father. The other three causes of a man are the material cause (flesh), the formal cause (form of man), and the final cause (end or purpose of human life). Only two of Aristotle’s causes answer to English usage—the efficient and the final causes. The Greek word translated as “cause” means something more like “responsible factor” or “necessary condition”.