resulting subjective phenomenon directly with the physical facts of immediate experience, we take a stand outside of ourselves and imagine the physical phenomenon to be some external affair conducted along our nervous system to a certain place where it is turned into a mental phenomenon. Now, this might all be very well if we had a satisfactory system of concepts for the physical world; our present representation of physical processes as entirely a matter of mechanics with concepts drawn from the muscle sense is not only unsatisfactory in physics, but leads to utter incomprehensibilities in matters of physiological psychology. We cannot represent brain processes in any way that will bring them into harmony with what we know as our facts of consciousness.
If we consider the physical phenomena as something quite outside of and incommensurate with the facts of our immediate experience, then, in the present state of our knowledge, we can readily agree that mental phenomena cannot be measured.[1] We can suppose that mental facts form a world of their own with which physical facts cannot be compared. But we have here broken up the facts as first given us into two classes, drawn hypotheses from the one set, and are now trying to bring the facts of the other class into harmony with hypotheses with which they will not agree.
There is one philosophical theory which goes a step further than this. So far, at least, we are all agreed as to the existence of a mental world governed by its own laws, but even this latter fact is denied by one class of objectors. This school, represented by numerous English and French writers and lately championed by Professor Muensterberg, would claim that no causal relations exist between mental phenomena, that after analyzing them into their elements we should next determine the brain processes to which they belong, and that the co-existence and sequence of mental phenomena find their explanation only in the relations of the brain processes.[2] Of the very naïve
