KNOWLEDGE, THEORY OF, that branch of philosophy which has for its province the investigation of the nature and structure of knowledge as such, with a view to determine the conditions of its possibility, and the significance, worth or validity of its contents as representing the nature and relations of the real.
It is only within a comparatively recent period that episte mology has come to he recognised as a distinct department of philosophical inquiry. Since the days of Kant, German thinkers have been in the habit of grouping under the head of Erkennt nistheorie a number of problems which belong together,—prob lems which have always, from the time of Plato, been included within the domain of philosophy. The term epistemology would appear to have been used for the first time in Ferrier's Institutes of Metaphysics, published in 1854. Philosophy according to Fer rier, consisted of two main divisions—epistemology, the doctrine or theory of knowing, and ontology, the science of that which truly is. Of these, the latter, he maintained, naturally comes to us first,—in the order of time, the proximate question of phil osophy has been that of the nature of real or ultimate being. But in the logical order the former comes first; we cannot even get a footing in ontology unless we have at least attempted to know what is. And we are not in a position to know what is, until we have found an answer to the questions—What is the meaning of to know? No sooner is the effort made to treat knowledge as itself the subject-matter of investigation than there comes to the front an antithesis that would seem to be of fundamental importance. There would seem, namely, to be implied in the very notion of knowledge a distinction and a relation between the inner or mental process of knowing and the outer world of fact, to which the act of knowing or cognising refers. To the former there has been as signed the technical name, the subjective, and to the latter the technical name, the objective. In all knowledge these two dis tinguishable aspects seem to be brought together into a certain unity. And we call the result which may be attained the acquisi
tion of truth—a term again involving in another way the antith esis of subjective and objective. Thus, three great fields of human research are at once indicated,—(a) the structure of the subjective process called knowing; (b) the specific character of the objects of the external world; and (c) the nature of truth, as discriminated alike from the mind that recognises it and from the facts which it is "about." The first belongs to psychology, the second forms the domain of the natural sciences and the third :7onstitutes the subject-matter of the theory of knowledge and logic.
The psychologist proposes to scrutinize the subjective aspect of knowledge,—the activity of knowing, as a condition of the individual mind, as so much matter of fact that can be inspected and analysed in the manner in which every other matter of fact, can be, and with respect to which there may be discovered uni formities of structure and of succession, uniformities which may be designated natural laws. These "states of consciousness" are, for him, so many events which happen at a definite time and in a definite set of connections with other psychical states. Take, for example, such a psychical event as the perception of a sense quality. The business of the psychologist is to determine its nature as a transient phase in the history of an individual mental life. If he deems it to be simple and irreducible, he needs to inquire how it stands related to those concomitant events which serve as occasions for calling forth its exercise. If he deems it to be complex, he needs to disengage the components of which it consists, and to find out how these are combined into the unity of the apparently simple act.