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That this objection is one I am not disinclined to recognize, will be inferred when I state that it is one I have myself raised. While preparing the second edition of the "Principles of Psychology," I found, among my memoranda, a note which still bore the wafers by which it had been attached to the original manuscript (unless, indeed, it had been transferred from the MS. of "First Principles," which its allusions seems to imply). It was this:

Why I omitted this note I cannot now remember. Possibly it was because reconsideration disclosed the reply that might be made to the contained objection. For, while it is true that the intellect cannot prove its own competence, since it must postulate its competence in the course of the proof, and so beg the question, yet it does not therefore follow that it cannot prove its own incompetence, in respect of questions of certain kinds. Its inability in respect of such questions has two conceivable causes. It may be that the deliverances of Reason in general are invalid, in which case the incompetence of Reason to solve questions of a certain class is implied by its general incompetence; or it may be that the deliverances of Reason, valid within a certain range, themselves end in the conclusion that Reason is incapable beyond that range. So that, while there can be no proof of competence, because competence is postulated in each step of the demonstration, there may be proof of incompetence either (1) if the