to knowable things—to the whole realm of possible objects of knowledge—is such that, whenever any matter of thought is clearly and distinctly conceived, the immediate judgments which the mind unhesitatingly affirms with regard to it are always true. As will presently appear, I do not hold a brief for the Cartesian criterion; on the contrary, I have no doubt whatever that the Cartesian criterion taken by itself is inadequate. All I urge is that its inadequacy is not established by Kant’s summary argument.
Let us turn to consider Kant’s sweeping negation in relation to a different criterion, laid down by Empiricists.
I take the principle of Empiricism, as an epistemological doctrine, to be that the ultimately valid premises of all scientific reasonings are cognitions of particular facts; all the generalisations of science being held to be obtained from these particular cognitions by induction, and to depend upon these for their validity. I do not accept this principle; I think it impossible to establish the general truths of the accepted sciences by processes of cogent inference on the basis of merely particular premises; and I think the chief service that J. S. Mill rendered to philosophy, by his elaborate attempt to perform this task, was to make this impossibility as clear as day. But I wish now to avoid this controversy; and, in order to avoid it, I shall take the Empirical criterion as relating only to particular cognitions; leaving open the question how far we also require universal premises in the construction of science.
The criterion is briefly discussed by Mill, Logic, book iv., chapter i., §§ 1, 2. It being understood that the validity of the general truths of the sciences depends on the correctness of induction from correct observation of particular facts, the question is what guarantee there is of the correctness of the observations?—in Mill’s words “we have to consider what is needful in order that the fact supposed to be observed may safely be received as true”. The answer is “in its first aspect,” very simple. “The sole condition is that what is supposed to have been observed shall really have been observed; that it be an observation—not an inference.” The fulfilment, indeed, of this sole and simple condition is not—as Mill goes on to explain—so easy as it may appear; “for in almost every act of our perceiving faculties, observation and inference are intimately blended; what we are said to observe is usually a compound result of which one-tenth may be observation and nine-tenths inference”. E.g., I affirm that I saw my brother at a certain hour this morning; this would commonly be said to be a fact known through the
