  Though the core of classic and mainstream natural law theory is thus untainted by any “naturalistic fallacy” (Finnis 2018, 2.4.2), non-practical knowledge of facts counts, in that theory, in various ways. Knowledge of the factual possibility of (say) acquiring knowledge, or of losing or saving life, is a datum (not really a premise) for the understanding that such a possibility is also an opportunity—that actualizing the possibility would be good for oneself and others. Other kinds of relevant facts include the facts about certain human radical capacities and their absence in other animals—these facts are the data for the insight into the sense and bounds of the class (persons, human beings) of “others” in “good for oneself and others.” Or again, facts about the limited supply of resources and the limited strength of human will (the need for incentives, etc.) make (1.5) appropriation of resources to particular owners a normal requirement of justice to non-owners and owners alike.