Project Gutenberg #20417
The Outline of Science, Volume 1
J. Arthur Thomson
1922Thomson's broad popular-science survey of astronomy, biology, and Earth science, prepared section by section from Project Gutenberg HTML.
Project Gutenberg #20417 Public domain in the United States Cover source Local typographic cover created for MojiMori from public-domain source metadata
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But how are we to know when to credit the animal with intelligence and when with something less spontaneous? Above all, how are we to know when the effective action, like opening the mouth the very instant it is touched by food in the mother's beak, is just a physiological action like coughing or sneezing, and when there is behind it—a mind at work? The answer to this question is no doubt that given by Prof. Lloyd Morgan, who may be called the founder of comparative psychology, that we must describe the piece of behaviour very carefully, just as it occurred, without reading anything into it, and that we must not ascribe it to a higher faculty if it can be satisfactorily accounted for in terms of a lower one. In following this principle we may be sometimes niggardly, for the behaviour may have a mental subtlety that we have missed; but in nine cases out of ten our conclusions are likely to be sound. It is the critical, scientific way.
Bearing this law in mind, let us take a survey of the emergence of mind among backboned animals.