Law schools do not teach students how to handle facts. In criminal law, injury law, contracts, civil rights--lawyers and judges rely on doctrines. Facts are intruding, though, historians and social scientists are expert witnesses, trial courts even ask for evidence of a law's purpose and rationality. How shall we deal with facts? Some reflections on probability, the Infield Fly Rule, Tit-for-Tat, and Tic-Tac-Toe.