In Aristotlian logic, a proposition of one of the four forms: all S is P; some S is P; no S is P; some S is not P. Also, a proposition that is not a conditional. As with the affirmative and negative, modern opinion is wary of this distinction, since what appears categorical may vary with the choice of a primitive vocabulary and notation. Appar-ently categorical propositions may also turn out to be disguised conditionals: X is intelligent (categorical?)=if X is given a range of tasks she performs them better than many people (conditional?). The problem is not merely one of classification, since deep metaphysical questions arise when facts that seem to be categorical and therefore solid, come to seem by contrast conditional, or purely hypothetical or potential. See also field.