 There is no direct evidence to explain Philo’s shift from radical to mitigated skepticism. But we can learn something about the general motivations he may have had for adopting his new position from the ways in which some mitigated skeptics understood the Carneadean notion of “persuasive impressions”. In the case of perceptual impressions, the difference between their view and the Clitomachian position is clarified by a criticism from Philo’s former student Antiochus that some Academics took persuasive impressions to be a criterion of truth, rather than just of action and philosophical criticism (see Sextus M 7.435–8 and Cicero Ac. 2.32–6). This shows that these Academics understood the mechanisms Carneades had outlined for increasing the persuasiveness of impressions to provide a means of confirming or disconfirming—in various degrees, though never ones that warranted them conclusively—whether they were likely to be true or not. These mitigated skeptics thus believed that the persuasiveness of perceptual impressions under the right perceptual and coherence conditions as defeasible, but rational, evidence for their truth. We find a similar move in the case of non-perceptual impressions: some mitigated skeptics formed tentative beliefs as to which positions are more likely to be true (see, e.g., Cicero Ac. 2.148), after using the standard Academic practice of arguing on either side of philosophical questions as a means of rationally evaluating arguments (see Cicero Ac. 2.7, 2.60 &amp; On the Nature of the Gods 1.11, Galen On the Best Method of Teaching ch. 1, and Plutarch Stoic Contradictions ch. 10). These mitigated skeptics thus changed the status of argument on either side from a critical practice ending in suspension of assent into a positive method for rationally confirming and, indirectly, teaching philosophical beliefs.