  Barnes’ argument, however, is fallacious (for more detailed discussion, see Schwab 2013, whose main points are summarised here). There are two fundamental flaws. First, the Hellenistic theory of the criterion of truth was never supposed to be a theory about how beliefs in general are formed, only beliefs which meet the condition of being suitable for conferring knowledge. But second, and more importantly, one needs to distinguish between suspending judgment on whether there is a criterion of truth, and failing to have a criterion of truth. Since the deliverances of the natural capacity of perception are criteria of truth according to the Epicureans, there is nothing one can do, short of putting one’s eyes out, to bring it about that one lacks this criterion of truth; merely suspending judgment on whether there is such a thing as a criterion of truth won’t do the job. Similarly, since it is cognitive impressions, according to the Stoics, which are criteria of truth, there is nothing one can do to bring it about that one lacks these criteria of truth, short of damaging one’s capacity for forming impressions (one’s phantasia); merely suspending judgment on whether there is a criterion of truth won’t do the job. Barnes actually acknowledges this flaw in his argument in a footnote:  