triangular question-mark signs with red borders Keith Lehrer, in his Theory of Knowledge, cautions against the sort of “commonsense” thinking prevalent among advocates of externalism, which is “The view that mental events and acts are essentially dependent on the world external to the mind, in opposition to the Cartesian separation of mental and physical worlds” (Oxford Living Dictionaries: English online, under word externalism). Should the pious heed his warning?

A little…critical circumspection shows that commonsense should not be allowed to run unbridled in the epistemic field….All sorts of perceptual beliefs, the belief that one saw a bear-print, for example, are considered justified when we have no great stake in the question of whether the belief is true or false. However, when a great deal (our personal safety, for example) hinges on the matter of whether the person saw a bear-print or something else, then we become instantly more cautious and exacting….Perceptual beliefs are considered innocent until proven guilty when we care not the least whether the belief is innocent or guilty. Once we do care, though, then we start to ask serious questions. (Keith Lehrer, Theory of Knowledge, 1990 Westview edition, 65.)

According to Lehrer, then, reliance on commonsense notions to guide our beliefs is a pragmatic maneuver, something we find convenient and practical for most situations. The question for the pious is to what extent this sort of pragmatism should be allowed to guide our beliefs in spiritual matters, upon which hinge much more than this-worldly personal safety.