SOFISMA. – In its primitive usage, σύριαμα (from σοφία, wisdom) denotes every discovery or invention of thought (inventum, scitum). After dialectic, through verbalistic devices (cf. the examples reported by Aristotle in the De sophisticis elenchis, ch. 4 ff.), was made by sophistry (v. SOFISTI) to serve negative purposes, the term s. also acquired a pejorative meaning and came to indicate an illogical (or false) argument that is apparently correct: “when it seems to prove, it will be a s., not a demonstration” (ἐν δὲ φαίνεται, σύριαμα ἔσται, οὐκ ἀπόδειξις: Top., VIII, 11, 162 a 14-15; cf. De soph. el., 1, 165 a 21; and Sextus Empiricus, Phyrrh. hypoth., II, 22, 229 ff.: “s. injure the truth by an appearance of plausibility”).
The further meaning acquired by the term, as an intentionally sophistical argument—for which s. is at times distinguished from a simple paralogism, or illogical argument—is likewise of sophistical derivation: this meaning is not explicit in Aristotle, who identifies s. and paralogism (De soph. el., 1, 164 a 21), but is nevertheless contained in the qualification of s. as a “contentious argument” (σύριαμα δὲ συλλογισμὸς ἐριστικὸς: Top., VIII, 11, 162 a 16-17; cf. 12, 162 b 3-5; cf. Reth., 1, 1355 b 17: “the sophist is such by deliberation,” κατὰ τὴν προάγειν) and in the assertion that the sophist aims to derive profit from an apparent science (De soph. el., 1, 165 a 22). The aforesaid meaning is instead expressed by the Latin term “fallacia” (from fallere, to deceive), used in the Middle Ages as a synonym for s. (although Seneca, following Cicero, had already rendered s. by “cavillatio”; cf. Ep., 111, and Cicero, Acad., IV, 24, 75: “sophismata appellantur fallaces conclusiunculae”; cf. also St. Augustine, De doctr. christ., II, ch. 34, no. 48). Finally, there is a third meaning—debatable, however—indicated by Lalande (Vocab. techn. et crit. de la philos., 5th ed., Paris 1947, pp. 989-90), according to which s. is an argument that, from true premises, or premises accepted as such, leads to impossible and paradoxical conclusions, yet does not appear refutable because it is logically correct: such, for example, according to some, are Zeno’s arguments or the Kantian antinomies. The existence of such s., according to Lalande, would show that the laws of logic “n'ont pas un champ d'application illimité” (loc. cit.).
A classification of the various forms of s., together with a detailed exposition of the methods for refuting them, is given by Aristotle in De soph. el., ch. 4 ff. Aristotle distinguishes the forms of s. deriving from expression or language (“secundum dictionem”): equivocation in terms; ambiguity of the sentence; variation in accent; passage from the divided sense of a proposition to the composite sense and vice versa; similarity of expression (cf. ch. 4, 165 b 24 ff.); and the forms extraneous to language (“extra dictionem”): attribution to the subject of what belongs only to one of its determinations, fallacia accidentis; taking in an absolute sense what is true only in a determinate sense, dictum simpliciter et dictum secundum quid; ignorance or confusion of the argument, ignorantia elenchi; error in inference, fallacia consequentis; assuming as a premise what is to be demonstrated, petitio principi; confusing what is not the cause with the cause, non causa pro causa; a complex question requiring contrary answers, proposed as a single question: sophisma plurium interrogationum ad modum unius (cf. ch.
5, 166 b 28 ff.). The Aristotelian classification was drawn from the practice of ancient sophistry. Among the further forms of s. not listed in Aristotle’s logic, and from which the methodology of modern science has not always been free, should be recalled: generalization based on an insufficient induction (sophisma inductionis) or on simple analogy (sophisma analogiae), and deductions from a hypothesis presented as certain truths (sophisma hypothesis).