 Plutarch wrote relatively little in the field of “logic” in the ancient sense (logikê), which includes philosophy of language and epistemology. This, however, does not necessarily point to a lack of interest or knowledge on his part. Quite the opposite is the case. Plutarch is particularly attracted to epistemology because he considers this as a crucial aspect of Platonist philosophy. He seeks to defend the epistemology of Academic skeptics like Arcesilaus and Carneades and on these grounds to advocate the unity of the Academy against the criticisms of Antiochus of Ascalon (1st c. BCE; see below, sects. 2 and 3). The Lamprias list of Plutarch's works contains one on Stoic logic (Reply to Chrysippus on the First Consequent, #152), and two on Aristotle's: On Aristotle's Topics in eight books (#56), and a Lecture on the Ten Categories (#192), all of them now lost. The latter two are indicative of a reawakening of interest in Aristotelian logic, beginning in the 1st c. BCE, cultivated mainly by Peripatetics such as Boethus and Andronicus, but also characterizing Platonists of Plutarch's era, such as Eudorus and Nicostratus, who set themselves in dialogue especially with Aristotle's Categories.  Although the content of these Plutarchean works remains unknown, we do have Plutarch's own claim that Aristotle's doctrine of categories is foreshadowed in the Timaeus (De an.  procr. 1023E; Timaeus 37b-c), which suggests that he considered Aristotelian logic a welcome development of relevant Platonic ideas (Karamanolis 2006, 123–125). Plutarch's interest in the Topics, on the other hand, must have been motivated by his interest in the dialectical methodology of arguing both sides of a question (Karamanolis 2006, 86–87; see further below, sect. 3), to which the Topics is devoted. Plutarch's works on epistemology cover a broad spectrum of issues. The question of the criterion of truth must have been central to works such as On How We Should Judge Truth (#225), What is Understanding?  (#144), That Understanding is Impossible (#146), none of which is extant today. The lost work Whether He Who Suspends Judgment on Everything is Led to Inaction (#158) must have confronted the common accusation against skepticism voiced in its title. Among Plutarch's surviving works important for understanding his epistemology are the Platonic Questions I and III, Against Colotes, On Common Notions, and On the Generation of the Soul 1024F-1025A (see below, sect.  3).