Consistency and Epistemic Probability Essay -- Argumentative Persuasiv

Consistency and Epistemic Probability ABSTRACT: Is consistency always epistemically virtuous? In this paper, I examine one threat to the traditional view that consistency is a minimum requirement for rational belief. Central to the argument is the notion of epistemic probability, understood as the degree of support or confirmation provided by the total available evidence. My strategy in examining this argument is to apply analogous reasoning to carefully tailored examples. The conclusions which emerge are substantive, informative and utterly implausible. I conclude, first, that the argument for inconsistency fails and, second, that it fails because epistemic probability does not conform to the axioms of the probability calculus. A plausible alternate model for determining degree of support is briefly considered. Is consistency always epistemically virtuous? Is it possible for a set of rational beliefs to be inconsistent? The traditional view has been that logical consistency is a minimum requirement for rational belief. Recently, this traditional view has been challenged, and is now in some disrepute. The issue is not only of interest in its own right, but also has bearing on several other aspects of our conception of justified belief. In particular, it is a critical issue for the coherence theories of justification which have been so prominent of late, for coherence is normally understood in such a way as to presuppose logical consistency. (1) Three distinct lines of argument against consistency can be discerned in the current discussion (although not always clearly distinguished there): (i) the paradox of the lottery, (ii) the fallibility argument, the core of which is an inference from my fallibility in the past to ... ...e Probable and the Provable (Oxford: Clarendon Press, 1977), 37. (7) Note that throughout this paper, an assumption has been made which is necessary for the epistemic probability argument, as well as the analogous arguments, namely, that there is a degree of confirmation less than 1 which is sufficient for justified belief. If this assumption were not granted, then, of course, no conclusion concerning warranted belief would follow. But the same arguments would show that, in the cases presented, there is strong confirmation that there is a natural therapy which cures AIDS (or that someone has exhibited psychic powers). And this conclusion is itself quite absurd. It can be avoided, however, only by rejecting the fit between degree of confirmation and the calculus. (8) This model for conjunction is endorsed by Pollock, op. cit., 248-49, and Cohen, op. cit., 221.