direct testimony of my senses. But the truth, Mill explains, is far otherwise; for I might have had visual sensations so similar as to be indistinguishable from those I actually had without my brother being there; I might have seen some one very like him, or it might have been a dream, or a waking hallucination; and if I had the ordinary evidence that my brother was dead, or in India, I should probably adopt one or other of these suppositions without hesitation. Now, obviously, “if any of these suppositions had been true, the affirmation that I saw my brother would have been erroneous”; but this does not, in Mill’s view, invalidate the Empirical criterion, for “whatever was matter of direct perception, namely, the visual sensations, would have been real”; my apparent cognition of this reality (he tacitly assumes) would have been a true and valid cognition. In short, only separate observation from inference and observation—or apparent knowledge obtained through observation—is absolutely valid and trustworthy; the idea that these are “errors of sense” is itself a vulgar error, or at least a loose thought or phrase; there are no errors in direct sense-perception, but only erroneous inferences from sense.
Now I shall presently consider how far this criterion, taken in any sense in which it would be available for its purpose, is completely trustworthy. But, however, that may be, it seems to me that Kant’s sweeping negative argument—which we are now examining—has really no force against its validity. No doubt, according to Kant’s general view of the form and matter of thought, this criterion, like the other, relates primarily to the form; for it rests on the distinction between two different functions of the knowing mind—Observation or Perception and Inference. But I see no reason to infer that it is therefore incapable of guaranteeing the material truth of Empirical cognition; or that the relation of the knowable world to the knowing mind cannot possibly be what Empiricism affirms it to be.
If now we contemplate together the two criteria that have been examined—the Cartesian and the Empirical—it is evident that, at least in its primary intention, neither alone covers the whole ground of the premises for which verification is primâ facie required. The Empirical criterion only verifies particular premises, and the Cartesian appears to be applied by its author primarily to universals—to what is “clearly and distinctly conceived by the pure understanding”.
This leads me to suggest that Kant has perhaps taken too strictly the demand for a “universal” (allgemein) criterion of truth. He has understood it to be a demand for some
