| On the contrary, scepticism is merely a means of awakening reason from its dogmatic dreams and exciting it to a more careful investigation into its own powers and pretensions. |
| But, as scepticism appears to be the shortest road to a permanent peace in the domain of philosophy, and as it is the track pursued by the many who aim at giving a philosophical colouring to their contemptuous dislike of all inquiries of this kind, I think it necessary to present to my readers this mode of thought in its true light. |
| Scepticism not a Permanent State for Human Reason. |
| The consciousness of ignorance--unless this ignorance is recognized to be absolutely necessary ought, instead of forming the conclusion of my inquiries, to be the strongest motive to the pursuit of them. |
| All ignorance is either ignorance of things or of the limits of knowledge. |
| If my ignorance is accidental and not necessary, it must incite me, in the first case, to a dogmatical inquiry regarding the objects of which I am ignorant; in the second, to a critical investigation into the bounds of all possible knowledge. |
| But that my ignorance is absolutely necessary and unavoidable, and that it consequently absolves from the duty of all further investigation, is a fact which cannot be made out upon empirical grounds--from observation--but upon critical grounds alone, that is, by a thoroughgoing investigation into the primary sources of cognition. |
| It follows that the determination of the bounds of reason can be made only on a priori grounds; while the empirical limitation of reason, which is merely an indeterminate cognition of an ignorance that can never be completely removed, can take place only a posteriorI. In other words, our empirical knowledge is limited by that which yet remains for us to know. |
| The former cognition of our ignorance, which is possible only on a rational basis, is a science; the latter is merely a perception, and we cannot say how far the inferences drawn from it may extend. |
| If I regard the earth, as it really appears to my senses, as a flat surface, I am ignorant how far this surface extends. |
| But experience teaches me that, how far soever I go, I always see before me a space in which I can proceed farther; and thus I know the limits--merely visual--of my actual knowledge of the earth, although I am ignorant of the limits of the earth itself. |
| But if I have got so far as to know that the earth is a sphere, and that its surface is spherical, I can cognize a priori and determine upon principles, from my knowledge of a small part of this surface--say to the extent of a degree--the diameter and circumference of the earth; and although I am ignorant of the objects which this surface contains, I have a perfect knowledge of its limits and extent. |
| The sum of all the possible objects of our cognition seems to us to be a level surface, with an apparent horizon--that which forms the limit of its extent, and which has been termed by us the idea of unconditioned totality. |
| To reach this limit by empirical means is impossible, and all attempts to determine it a priori according to a principle, are alike in vain. |
| But all the questions raised by pure reason relate to that which lies beyond this horizon, or, at least, in its boundary line. |
| The celebrated David Hume was one of those geographers of human reason who believe that they have given a sufficient answer to all such questions by declaring them to lie beyond the horizon of our knowledge--a horizon which, however, Hume was unable to determine. |
| His attention especially was directed to the principle of causality; and he remarked with perfect justice that the truth of this principle, and even the objective validity of the conception of a cause, was not commonly based upon clear insight, that is, upon a priori cognition. |
| Hence he concluded that this law does not derive its authority from its universality and necessity, but merely from its general applicability in the course of experience, and a kind of subjective necessity thence arising, which he termed habit. |
| From the inability of reason to establish this principle as a necessary law for the acquisition of all experience, he inferred the nullity of all the attempts of reason to pass the region of the empirical. |
| This procedure of subjecting the facta of reason to examination, and, if necessary, to disapproval, may be termed the censura of reason. |
| This censura must inevitably lead us to doubts regarding all transcendent employment of principles. |