Another kind of presumption arises from “what happens mostly” (a kind of reasoning that we see also in Aristotle, Cicero, and the Greek medical writers). Decisions can be based on such well-known generalizations as “One does not ordinarily pay a debt before term” (though exceptions are recognized as common enough), “Most women’s pregnancies last nine months,” “Most children will turn out to be fertile.”19 Such presumptions may conflict, in which case a distinction needs to be drawn to see which is applicable.
