  Epicurus (late 4th–early 3rd c. BCE) and the Epicureans are said to have rejected logic as an unnecessary discipline (D. L. 10.31, Usener 257). This notwithstanding, several aspects of their philosophy forced or prompted them to take a stand on some issues in philosophical logic. (1) Language meaning and definition: The Epicureans held that natural languages came into existence not by stipulation of word meanings but as the result of the innate capacities of humans for using signs and articulating sounds and of human social interaction (D. L. 10.75–6); that language is learnt in context (Lucretius 5.1028ff); and that linguistic expressions of natural languages are clearer and more conspicuous than their definitions; even that definitions would destroy their conspicuousness (Usener 258, 243); and that philosophers hence should use ordinary language rather than introduce technical expressions (Epicurus On Nature 28). (2) Truth-bearers: the Epicureans deny the existence of incorporeal meanings, such as Stoic sayables. Their truth-bearers are linguistic items, more precisely, utterances (phônai) (S. E. M 8.13, 258; Usener 259, 265). Truth consists in the correspondence of things and utterances, falsehood in a lack of such correspondence (S. E. M 8.9, Usener 244), although the details are obscure here. (3) Excluded middle: with utterances as truth-bearers, the Epicureans face the question what the truth-values of future contingents are. Two views are recorded. One is the denial of the Principle of Excluded Middle (‘p or not p’) for future contingents (Usener 376, Cicero Acad. 2.97, Cicero Fat. 37). The other, more interesting, one leaves the Excluded Middle intact for all utterances, but holds that, in the case of future contingents, the component utterances ‘p’ and ‘not p’ are neither true nor false (Cicero Fat. 37), but, it seems, indefinite. This could be regarded as an anticipation of supervaluationism. (4) Induction: Inductive logic was comparatively little developed in antiquity. Aristotle discusses arguments from the particular to the universal (epagôgê) in the Topics and Posterior Analytics but does not provide a theory of them. Some later Epicureans developed a theory of inductive inference which bases the inference on empirical observation that certain properties concur without exception (Philodemus De Signis).