 These reasons, then, or something like them, led Philo, along with other mitigated skeptics, to the formal position that, while nothing could be known (as shown by the Academic arguments against the possibility of cognitive impressions), it is nevertheless rational to assent under certain conditions, i.e., to hold beliefs based on reasons (Cicero Ac. 2.78). The mitigated skeptics retained the Stoic characterization of such beliefs as “opinions” to mark the fact that, despite the rational grounds they had for holding them, they were just rational beliefs—i.e., they did not amount to “cognitions” or knowledge (Cicero Ac. 2.148). But they also distinguished rational opinions of this sort from the general Stoic category of opinion as any assent to a non-cognitive impression (and hence as always bad), by qualifying their assent to them as “measured”—that is, as provisional on their avowedly inconclusive evidence, rather than as a straightforward commitment to their truth. (See the anonymous Introduction to Plato ch. 7 and Gellius Attic Nights 11.5.8. Sextus mis-ascribes this view to Clitomachus in PH 1.226 &amp; 1.229–30.)