It may seem that we have not come far toward stating what we may fairly mean by saying that a fact is given in experience. We have at least made out that the test of perception is not a sufficient one. Some objects seem to be facts of experience, when the ideas of them come home to us in a certain way, when they have what has been called ‘reality feeling.’ Even an object of sense-perception needs the tone of reality in order to be quite unambiguous. One can at least ask the question, ‘Is this a real house or the illusion of a house, which I see?’ An hallucination may be all but perfect, and differ from a genuinely perceived object only in its tone of reality. “An hallucination,” says Professor James, “is a strictly sensational form of consciousness, as good and true a sensation as if there were a real object there.” The poor tinker Sly, in Taming of the Shrew, who for a jest is made to believe himself a lord, is the victim of a shifting reality-feeling.
“Am I a lord? And have I such a lady?
Or do I dream? Or have I dreamed till now?
I do not sleep: I see, I hear, I speak;
I smell sweet savours, and I feel soft things:
Upon my life I am a lord indeed
And not a tinker, nor Christophero Sly.”
To sum up. For a fact to be an object of experience it is not necessary that it be perceived or be of a sort that could possibly be perceived. It is not necessary that it exist or be of a sort that could possibly exist.
I have suggested ‘reality-feeling’ as the sort of criterion that may help us to characterize an object of experience. In spite of all the uncertainties of experience we say it is the surest basis of knowledge and the only foundation for theory. A priori knowledge, if there be such, I include within experience. To have an object of experience is to know that object in some respect. The object may not exist, but that makes no difference to the experience that ‘knows’ it. What I wish now to examine is the relation of ‘reality-feeling’ to knowledge as a case of experience.
The discussion thus far has been carried on from the point of view of Avenarius and here I shall attempt some account of the way in which Avenarius describes the experience of knowing something. His opinions will illustrate important phases of our problem, and bring out the empirical detail of the situation with which we have to deal.
Avenarius gives an elaborate analysis of the feeling-tones which