This part of the logic which contains the Doctrine of the Notion and constitutes the third part of the whole, is also issued under the particular title System of Subjective Logic, for the convenience of those friends of this science who are accustomed to take a greater interest in the matters here treated and included in the scope of logic commonly so called, than in the further logical topics treated in the first two parts. For these earlier parts I could claim the indulgence of fair-minded critics on account of the scant preliminary studies in this field which could have afforded me a support, material, and a guiding thread. In the case of the present part, I may claim their indulgence rather for the opposite reason; for the logic of the Notion, a completely ready-made and solidified, one may say, ossified material is already to hand, and the problem is to render this material fluid and to re-kindle the spontaneity of the Notion in such dead matter. If the building of a new city in a waste land is attended with difficulties, yet there is no shortage of materials; but the abundance of materials presents all the more obstacles of another kind when the task is to remodel an ancient city, solidly built, and maintained in continuous possession and occupation. Among other things one must resolve to make no use at all of much material that has hitherto been highly esteemed.
But above all, the grandeur of the subject matter may be advanced as an excuse for the imperfect execution. For what subject matter can cognition have that is more sublime than truth itself! Yet the doubt whether it is not just this subject matter that requires an excuse may occur to us if we recall the sense in which Pilate put the question, What is truth? In the words of the poet: 'With the courtier's mien that purblind yet smiling condemns the cause of the earnest soul.' Pilate's question bears the meaning — which may be regarded as an element in good manners — together with a reminder of it, that the aim of attaining truth is, as everyone knows, something given up and long since set aside, and that the unattainableness of truth is recognised even among professional philosophers and logicians. But if the question that religion raises as to the value of things, insights, and actions — a question which in its import has a like meaning — is once more vindicating its claims in our days, then philosophy must surely hope that it will no longer be thought so strange if it, too, in its immediate domain once more asserts its true aim, and, after having lapsed into the manner and method of other sciences and their renunciation of the claim to truth, strives to rise again to that aim. In respect of this attempt, it is not, strictly speaking, permissible to offer any apology; but in respect of the execution, I may plead in excuse that my official duties and other personal circumstances allowed me but scattered hours of labour at a science that demands and deserves undistracted and undivided exertion.
Nuremberg, July 21, 1816