Explicit rabbinic legal concepts and principles—notions such as “multiple causation is prohibited/permitted” (zeh ve-zeh gorem muttar/ءasur), “retrospective determination of reality is/is not valid” (yesh/ءein bererah), and the like—occur frequently in the Babylonian Talmud (BT), especially in the later strata of that work.See generally Leib Moscovitz, Talmudic Reasoning: From Casuistics to Conceptualization (Tübingen: Mohr Siebeck, 2002), especially pp. 292–342, with extensive references to earlier literature. Most concepts and principles of this sort are applied to a case or two, although we sometimes find extended conceptual sugyot in BT that systematically analyze a particular legal principle. Such passages generally analyze a group of tannaitic sources in light of the specified principle, which is assumed to apply to all the cases cited; these cases may be adduced either to support or to refute the relevant principle.