CONTINGENCY. — In its generic sense, c. is the occurrence of “both necessary and non-necessary or possible” (Aristotle, *Anal. Pr.*, I, 3, 25 a 37). In philosophical usage, it denotes the opposite of what is necessary and is therefore nearly synonymous with “possible,” with “that which can be or not be,” within the realm of thought, being, or becoming. Waitz maintained a clear distinction between “possible” and c., but the prevailing opinion, defended by H. Maier (*Die Syllogistik des Aristoteles*, I, Tübingen 1896, p. 194), is that Aristotle uses the two terms as synonyms (*Anal. Pr.*, I, 10, 13, 15, 21; *Anal. Post.*, I, 6, 74 b 38) and that the criteria given for one are those given for the other (*Anal. Pr.*, I, 13, 32 a 18; *Physic.*, VIII, 1, 243 a 11; *Met.*, X, 3, 1047 a 26). The only difference is that c. emphasizes more the fact that possibility is rooted in a real “substratum” (cf. W. D. Ross, *Aristotle’s Metaphysics*, II, Oxford 1928, p. 245).
In logic, propositions in which the connection between subject and predicate is indifferent are called contingent: “the man is white,” “Socrates walks” (*Anal. Pr.*, I, 13, 32 a 18). In metaphysics, a distinction is made between a c. to exist and a c. to act; all modalities of c. are traced back to two roots: “matter” for bodies and “freedom” for spiritual substances. If everything were necessarily determined, the mechanists and fatalists would be right, but this is not the case (*De Interpr.*, 9, 19, a 7 ff.). Since “prime matter” is pure potency, it is and remains by itself disposed to receive all “forms” of bodies. Therefore, when it is under one form, it is not bound to it forever, but remains in potency to all other forms, under which it can in fact successively pass when, through the action of contrary qualities, the body is corrupted and a new substance is generated. C. is thus synonymous with “corruptibility”: “Quod aliqua quandoque sint et quandoque non sint, habent ex materia in quantum subicitur privationi vel formae” (St. Thomas, *Comm. in De Coelo et Mundo*, I, lect. 29, ed. Parm., XIX, p. 75a). Hence, spiritual substances, which in Thomistic metaphysics lack any matter, are not to be called contingent but necessary (or immortal): “Ea vero quae ab eo sic producta sunt ut in sempiternum sint, habent potentiam et virtutem ad semper essendum et nullo modo ad hoc quod aliquando non sint” (ibid., p. 75b; *De Pot.*, q. 5, a. 3; *C. G.* III, 30): a doctrine that underlies the third way (*Sum. Theol.*, 1a-2ae, q. 3). Neoscholastics usually adhere to the vague Wolffian meaning of c., as synonymous with what is finite and created.
C. in acting is spoken of both in the corporeal and spiritual orders. Intelligent substances, whose adequate object of operation and striving is the universal Good, remain “free” with respect to particular finite goods and means not necessary to the ultimate end. But even in the corporeal world, contingent causes occur. While some effects proceed necessarily (naturally) because they are characteristic of a given nature, others it is inclined toward but can be hindered by the intervention of another cause; still others it is only remotely in potency and is not determined to one rather than another except by the concurrence (*concursus*) of other causes or by the occurrence of certain precise conditions that are likewise contingent (St. Thomas, *Comm. in Periherm.*, I, lect. 13-14, ed. Parm., XVIII, p. 30 ff.). This is what is called happening by “chance” (in natural events) or “fortune” (in human affairs).
Boutroux (v.), in an attempt to safeguard human freedom, proposed a “philosophy of c.” according to which in the world of both bodies and spirits there is no law that is absolute necessity: “The supreme principles of things would still be laws, but moral and aesthetic laws, more or less immediate expressions of divine perfection” that is pure and perfect “spontaneity” to which all creatures participate, though in different forms and degrees (p. 169).