 Of course, even provided with a solution to the problem of error dispositionalism might come to grief with Kripke’s skeptic. Solving the problem of error requires showing that there is a plausible principle \(P\) assigning meanings to expressions on the basis of the speaker’s dispositions to use them, a principle underwriting plausible ascriptions of error. On a quite plausible interpretation of the skeptic’s main strategy—i.e., that of “quussing” candidate facts—this strategy is as applicable here as elsewhere. If, for instance, \(P\) assigns addition to “plus” on the basis of disposition \(D\), the skeptic will want to know why this is the right principle—as opposed to some other principle \(P'\) assigning quaddition to “plus” on the basis of \(D\). As the mere fact of the speaker’s having \(D\) does nothing to determine which of these principles is the right one, dispositional facts are as quussable as any of the other candidates—and this remains the case even if your dispositionalism comes with a plausible principle of meaning determination (cf. Pagin 2002:  160f).[19]