In regard to the _statement_ of the problem, it is necessary, in the first instance, to ascertain its precise import, by determining the meaning of the term Certitude. The programme of the Academy very properly places this question on the foreground, Is Certitude the same with the highest probability? And it is the more necessary to give precedence to this part of the inquiry, because it is notorious that there is a wide difference between the philosophical and the popular sense of Certitude,--a difference which has often occasioned mutual misunderstanding between disputants, and a profitless warfare of words. In the philosophical sense of the term, that only is said to be _certain_ which is either an axiomatic truth, intuitively discerned, or a demonstrated truth, derived from the former by rigorous deduction; while all that part of our knowledge which is gathered from experience and observation, however credible in itself and however surely believed, is characterized as _probable_ only. In the popular sense of the term, Certitude belongs to all those truths, of whatever kind and in whatever way acquired, in regard to which we have no reason to be in doubt or suspense, and which rest on sufficient and satisfactory evidence. A philosopher is _certain_, in his sense of the term, only of what he intuitively perceives or can logically demonstrate; a peasant is _certain_, in his sense of the term, of whatever he distinctly sees, or clearly remembers, or receives on authentic testimony. There is much reason, we think, to regret the existence of such a wide difference between the philosophical and the popular sense of an expression, which must occur so often both in speculative discussion and in the intercourse of common life. It may be doubted whether the metaphysician is entitled to borrow the language of society, and to engraft upon it an arbitrary definition of his own, different from and even inconsistent with that which it bears in common usage. Nor can he plead necessity as a sufficient excuse, or the accuracy of his definition as an effectual safeguard, since, however needful it may be to discriminate between _different species_ of Certitude, by marking their peculiar characteristics and respective sources, surely this might be done more safely and satisfactorily by designating one kind of it as Intuitive, another as Demonstrative, another as Moral, or Experimental, or Historical, than it can be by any arbitrary restriction of the _generic_ term to one or two of the many species which are comprehended under it. No doubt there is a real distinction, and one of great practical importance, between _certitude_ and _probability_; but this distinction is not overlooked in the language of common life;--it is only necessary to determine what truths belong respectively to each: whereas when all the truths of Experience, and even, in some cases, those of scientific Induction, are ranked under the head of _probability_ merely, is it not