contingent truths is the strangest thing imaginable. How does he class them? In this way—first, necessary truths, secondly, contingent truths. And how does be divide the necessary truths? He again divides them into necessary and contingent truths!—the first class of this subdivision being necessary, he says, "with the necessity which hinders us from believing a contradiction" (Exam. p. 8): the second class being necessary "with the necessity which constrains us to accept these first principles as laws of thinking"—that is, being necessary with the necessity of contingency! Is not that an amusing division? It is exactly like this: we first divide human beings into men and women, and then we subdivide the men into men and women! It must be admitted, however, that Mr Cairns picked up this confusion from Sir W. Hamilton (pace tanti viri), who lays down the distinction very much in this manner in his edition of Reid's works, p. 754. Mr Cairns cannot be original even in his blunders; he is original only in his fabrications.
The whole of Mr Cairns' objections to my method amount merely to this: that I am wrong in applying to philosophy the method of demonstration. This objection is foreseen and obviated in the Introduction to the "Institutes," § 37, where it is said that the propriety of this application must be determined by its success. It would have been more satisfactory, therefore, if Mr Cairns, instead of indulging in general assertions that the method did not apply, had adduced a single instance in which it had proved unsuccessful. He prefers, however, to throw distant shots, which fall greatly short of the mark, knowing well that if he were to venture into close quarters with the system, it would grind him up in a twinkling.
Objecting to my method, Mr Cairns continues, "It is perfectly possible that there may be necessary truths not contained demonstrably in any one such truth" (as my first proposition). This is not only perfectly possible—it is perfectly certain—the necessary truths of geometry are not contained demonstrably in my first principle. But let us suppose the statement limited to the necessary truths in regard to "Knowing and Being"—what
