From The Art and Popular Culture Encyclopedia
Moral certainty is a concept of intuitive probability. It means a very high degree of probability, sufficient for action, but short of absolute or mathematical certainty.
The concept stems from a statement in Aristotle's Nicomachean Ethics that one must be content with the kind of certainty appropriate to different subject matters, so that in practical decisions one cannot expect the certainty of mathematics. The Latin phrase moralis certitudo was used in this sense by the French philosopher Jean Gerson about 1400. The Oxford English Dictionary mentions occurrences in English from 1637. In law, it has been associated with verdicts based on certainty beyond a reasonable doubt.