Page:Ferrier's Works Volume 1 - Institutes of Metaphysic (1875 ed.).djvu/58

30 falser. If the element of demonstration were subtracted, there cannot be a doubt that many systems would appear to be much truer than this one.

§ 36. The general character of this system is, that it is a body of necessary truth. It starts from a single proposition which, it is conceived, is an essential axiom of all reason, and one which cannot be denied without running against a contradiction. The axiom may not be self-evident in an instant; but that as has been remarked, is no criterion. A moderate degree of reflection, coupled with the observations by which the proposition is enforced, may satisfy any one that its nature is such as has been stated. From this single proposition the whole system is deduced in a series of demonstrations, each of which professes to be as strict as any demonstration in Euclid, while the whole of them taken together constitute one great demonstration. If this rigorous necessity is not their character to the very letter,—if there is a single weak point in the system,—if there be any one premiss or any one conclusion which is not as certain as that two and two make four, the whole scheme falls to pieces, and must be given up, root and branch. Everything is perilled on the pretension that the scheme is rigidly demonstrated throughout; for a philosophy is not entitled to exist, unless it can make good this claim.