Kinds of knowledge

(1) It is impossible that all the knowledge a man has acquired should be at once present inconsciousness. The greater part, in fact all of it with the exception of the few thoughts actually present in the mind, is stored up in the form of latent dispositions which enable the mind to recall it when wanted. Hence we may distinguish actual from habitual knowledge. The latter extends to whatever is preserved in memory and is capable of being recalled at will. This capacity of being recalled may require several experiences; a science is not always known after it has been mastered once, for even then it may be forgotten. By habitual knowledge is meant knowledge in readiness to come back to consciousness, and it is clear that it may have different degrees of perfection.

(2) The distinction between knowledge as recognition and knowledge as understanding has already been noted. In the same connection may be mentioned the distinction between particular knowledge, or knowledge of facts and individuals, and general knowledge, or knowledge of laws and classes. The former deals with the concrete, the latter with the abstract.

(3) According to the process by which it is acquired, knowledge is intuitive and immediate or discursive and mediate. The former comes from the direct sense perception, or the direct mentalintuition of the truth of a proposition, based as it were on its own merits. The latter consists in the recognition of the truth of a proposition by seeing its connection with another already known to betrue. The self-evident proposition is of such a nature as to be immediately clear to the mind. No one who understands the terms can fail to know that two and two are four, or that the whole is greater than any one of its parts. But most human knowledge is acquired progressively. Inductive knowledge starts from self-evident facts, and rises to laws and causes. Deductive knowledge proceeds from general self-evident propositions in order to discover their particular application. In both cases the process may be long, difficult, and complex. One may have to be satisfied with negative conception and analogical evidence, and, as a result, knowledge will be less clear, less certain, and more liable toerror. (See DEDUCTION; INDUCTION.)