ABSTRACT
In our previous studies of constructive reasoning, we have seen that the evolution of such reasoning presents itself under two different aspects, depending one upon the other—the passage from the concrete phase to a phase which is always more abstract, and that from elementary reasoning, conceived at the outset by a single intuitive act, to the lengthy and complicated process of logical deduction, properly so called. The first passage is due, as we have seen, to the discovery of concepts of an order always more general, that is to say, to the recognition of classes or groups, which are always more extensive, of phenomena or objects, equivalent in relation to a given end or to the result of a given piece of reasoning. This formation of new concepts, or extension of old concepts, increases, as we have shown, the number of operations or experiments, the results of which we know beforehand and which can in consequence be simply imagined. At the same time, thanks to the reduction of all the phenomena comprised in a given concept to the attribute or group of attributes only, which makes them equivalent under such and such an aspect, the operations or experiments to be performed on the schematized phenomenon, which thus come to represent the particular concept, are rendered so much the simpler. The reasoner profits, then, by this ever-increasing number of operations or experiments, of which he knows the outcome in advance, and also by the greater simplicity of the operations or experiments to be conducted mentally, in order to imagine and link together an ever-increasing number of experiences, and to complicate and prolong the process of combination; which is precisely the application, always in a larger measure, of the deductive method.
