334 VI. ON PSYCHOPHYSIOLOGY
2) That the signals and symbols may have different orders, indicating superimposition of stimuli;
3) That animals cannot extend their responses to signals of higher order indefinitely;
4) That humans can extend their semantic responses to higher order symbols indefinitely, and, in fact, have done so through language which is always connected with some response, be it only repression or some other neurotic or psychotic manifestations.
The above extension is structurally fundamental, because we can extend the vocabulary of conditional reactions to humans in all their functions. Without it, we find ourselves saddled with a vocabulary which does not correspond in structure to the well-known elementary facts concerning human responses to stimuli, and we relapse into the old 'behaviourism', which is structurally insufficient.
The present system is based on such observations and extensions. It was reached independently from structural and physico-mathematical considerations. With this structural verbal extension, we can easily be convinced that everything that we call 'education', 'habits', 'learning'., on all levels is building up acquired or conditional and s.r of different orders, as one of the differences between 'man' and 'animal' consists in the fact that humans can extend their symbolism and responses to indefinitely high orders, while with animals this power of abstracting and response stops somewhere. We establish here a sharp distinction between the high abstractions 'man' and 'animal', and so build up a psychophysiological and structurally satisfactory language.
It is obvious that the fundamental means which man possesses of extending his orders of abstractions indefinitely is conditioned, and consists in general in symbolism and, in particular, in speech. Words, considered as symbols for humans, provide us with endlessly flexible conditional semantic stimuli, which are just as 'real' and effective for man as any other powerful stimulus.
Take, for instance, the example of the World War! Would the men in the trenches have endured at all the horrors they had to live through if it had not been for words, and, neurologically speaking, because of the conditional s.r connected with words? 'If any question why we died, Tell them, because our fathers lied.' said the poet truly, and experience shows it is not limited to the trenches.2
In interpreting the experiments on animals as applied to humans, it should be remembered that some of the experiments of Pavlov, as they stand, would be, at the least, neurotic for man. The reason for this is