Page:Philosophical Review Volume 1.djvu/428

412 be the same with pain as with pleasure. From which it is plain that the physical activity of the pain or the pleasure should be separate from that of the touch. That is, when we have a touch and a pain we should account for them by two separate distinct processes, and the same for touch and pleasure. In view of this it seems hardly necessary to ask which should be the most reasonable of our two doctrines. According to the traditional view, these separate activities must be supposed to go on in the same nerve simultaneously. By the doctrine of specific nerves, each goes on in a separate nerve. This is the crucial difference between the rival theories.

But the traditional view not only holds that pleasure and pain are inseparable attributes of other sensations, but that they are inverse and excluding complements of each other; that they are two ends or polar aspects of a single phenomenon. One of the most conclusive tests of nerve functions is that, when their terminals are electrically stimulated, each responds with its proper sensation. In this way Goldscheider's pain nerves give pain; and if pleasure and pain are polar complements surely these same nerves ought in some way to give us pleasure, if any nerves should. If some opposite phase of the same kind of stimulation as causes pain should give pleasure say, a gentle and gradually applied current for pleasure in contrast to a sudden and strong current for pain this would be strong evidence for the polar doctrine. But this never happens: these Goldscheider nerves give only pain, however stimulated; most surely do they never give pleasure. This is not a final demonstration against the traditional view, but it is unfortunate for that doctrine that its strongest evidence fails just where it might be expected to appear.

This brings us to the strongest point to be urged against the doctrine of specific nerves for pleasure. Not only will Goldscheider's pain nerves not respond with pleasure to direct stimulation, but neither will any known single nerve in the body do this. No specific nerves of pleasure have yet been found. We must go further than this and declare that no pleasure sensation, in strict conformity with our definition of a sensation,