 Be this as it may, even if rule-circularity is neither vicious nor otherwise problematic, one may still wonder how Boyd’s argument is to convert a critic of abduction, given that it relies on abduction. But Psillos makes it clear that the point of philosophical argumentation is not always, and in any case need not be, to convince an opponent of one’s position. Sometimes the point is, more modestly, to assure or reassure oneself that the position one endorses, or is tempted to endorse, is correct. In the case at hand, we need not think of Boyd’s argument as an attempt to convince the opponent of abduction of its reliability. Rather, it may be thought of as justifying the rule from within the perspective of someone who is already sympathetic towards abduction; see Psillos 1999 (89).