Logic, in our opinion, should reject this demand, the origin of which lies in the confusion between thought in general and thought as the science of thought. The categories are certainly affirmed in the individual judgment, but Logic, as the science of thought, does not undertake to formulate judgments which will say what are the predicable terms, the ultimate or pure concepts, the categories, with which reality is thought. Logic cannot claim to substitute itself for the other philosophic sciences and itself to solve all the problems which offer themselves to thought as to the nature of reality. Its scope is to define categories and to formulate judgments _only on that aspect of Reality, which is logical thought._ It is, therefore, under the obligation to face the question as to whether there be logical categories, supreme concepts or supreme predicables from the point of view of logic, and if there be, to indicate and to deduce them. It is not obliged to indicate and to deduce all the supreme predicables and categories. [Sidenote: _The uniqueness of the logical category: the concept._] Now we have already treated of the question as to the categories of Logic and have solved it, partly affirmatively, partly in the negative. That is to say, we have denied to Logic a multiplicity of categories, since the three fundamental categories, usually given as concept, judgment, and syllogism, have been revealed to be identical. The others, derived from formalist Logic and relating to classes of concepts, to forms of judgments and to figures of the syllogism (and even these three preceding, if they are taken as separable or distinguishable), have been shown to be empirical and arbitrary. Finally, those that were based upon the gnoseology of the pseudoconcepts have shown themselves to be extraneous to pure Logic. On the other hand, we have affirmed the category proper to Logic,--the unique category to which it gives rise. It has been defined as the pure concept, at once judgment of definition and individual judgment, the logical _a priori_ synthesis. Thus the enquiry can be looked upon as exhaustive as regards this part of the subject. [Sidenote: _The other categories. No longer logical, but real. Systems of categories._]