Abstract

The abandonment of sole reliance on the logical positivist canon of wholly general, topic-neutral, a priori inference principles has created a pressing need for a principled way to set limits on the demand for justification. I diagnose the problems with several contemporary proposals via two case studies, the first concerned with the possibility of groundlessly rational theism, and the second with the use of groundlessly rational commitments in defense of scientific rationality. ;I argue that William Alston's appeal to the "practical" rationality of engaging in a socially established belief-forming practice and Alvin Plantinga's defense of properly basic belief in God are overly permissive. Alston's position gives too much scope to pragmatic and social considerations, while Plantinga's rejection of polemically useful epidemic principles leaves him with an implausible externalism about rationality as the only way to block irrationality. In the case of scientific rationality, I argue that Bas van Fraassen's "liberal probabilism" gives too much scope to tradition and pragmatic factors, while Richard Boyd's methodological argument for scientific realism gives too much weight to the successful use of theories that happen to belong to one's own scientific tradition. ;In the light of these defects, I argue that the only propositions that don't require justification are "hinge-propositions"--topic-specific, defeasible principles that express conceptual competence conditions--because groundless doubt of them is either irrational or betrays lack of conceptual grasp. ;This account provides adequate fundamental principles for science, but sets strict limits to groundless rationality. For example, theistic belief-forming practices can't be groundlessly rational because they involve an unjustified departure from the application of the concept of a person in response to experience. ;I defend the closure claim that hinge-propositions are the only kind of groundlessly rational propositions by arguing that this account provides the best explanation for our shared uncontroversial judgments of rationality and irrationality. My account makes the strongest demands for justification that are compatible with our shared and secure judgments of prima facie rationality and the weakest demands for justification that are compatible with our shared and secure judgments about epistemically responsible beliefs