This paper discusses ἐπιβολαὶ τῆς διανοίας, which later Epicureans are supposed to have elevated to a fourth criterion of truth to complement perceptions, preconceptions and feelings. By examining Epicurus’ extant writings, the paper distinguishes three different senses of the term: ‘thought in general’, ‘act of attention’ and ‘mental perception’. It is argued that only the sense ‘mental perception’ yields a plausible reading of ἐπιβολαί as a criterion of truth. The paper then turns to the textual evidence on ἐπιβολαί in later (...) authors. While the term ἐπιβολή is not used by Cicero, Lucretius and Philodemus in the sense of mental perception, it is argued that this still is the most plausible way of understanding ἐπιβολή as a criterion of truth. (shrink)

In his refutation of skepticism in book IV of De rerum natura, Lucretius uses argumentative methods typical of Epicurus: the περιτροπή is in many ways similar to that used by the philosopher in book XXV of Περὶ φύσεως, the same book where, in a passage dedicated to the criticism against determinists, can be found a reference to the criterion of the πρόληψις, that Lucretius exploits in his refutation. Moreover, Lucretius develops a strong demonstration concerning the irrefutability of αἴσθησις as a (...) criterion of truth, which finds significant points of contact with a large fragment, transmitted by Diogenes Laertius and generally traced back to the Canon of Epicurus. The last argument used by the poet is a pragmatic one: for the skeptic it would be impossible to live. The argument is similar to the praxis-based argument used by Epicurus in the Περὶ φύσεως against the partisans of determinism. But the pragmatic argument goes back to a very ancient layer of anti-skeptical polemics, even prior to Epicurus and already present in book Γ of Aristotle’s Metaphysics. Although later influences cannot be excluded, Lucretius appears to be a faithful witness of Epicurus. Probably in a lost section of the Περὶ φύσεως, the philosopher of Samos showed positions going against skeptical or proto-skeptical attitude, contemporary or earlier to the time of the philosopher, probably developed in a Democritean or a Socratic context. Epicurus’ ad hominem strategy is very close to that of the philosopher in the Principal Doctrines XXIII–XXV, and certainly follows Aristotle’ strategy in book Γ of Metaphysics against those who deny the principle of non-contradiction. In a similar way, Epicurus does not have one figure as the objective of his refutation but constructs a hypothetical dialectical opponent capable of embodying a series of philosophical tendencies judged by the founder of Kepos to be extremely dangerous not only for the correct exercise of thought but for the human being’s life itself. (shrink)