Life and Mechanism.—But are not all biologists confronted with the difficulty that gave Herbert Spencer pause? Physiological analysis has done much in revealing chains of sequence within the organism, but no vital phenomenon has as yet been redescribed in terms of chemistry and physics. Again and again some success in discovering physico-chemical chains of sequence has awakened the expectation that the dawn of a mechanical theory of life was drawing nigh, but the dawn seems further off than ever. The residual phenomena left uninterpreted by mechanical categories loom out more persistently than they did a century ago. As Bunge once said "the more thoroughly and conscientiously we endeavour to study biological problems, the more are we convinced that even those processes which we have already regarded as explicable by chemical and physical laws, are in reality infinitely more complex, and at present defy any attempt at a mechanical explanation." As Dr J. S. Haldane puts it: "If we look at the phenomena which are capable of being stated, or explained in physico-chemical terms, we see at once that there is nothing in them characteristic of life.... The action of each bodily mechanism, the composition and structure of each organ, are all mutually determined and connected with one another in such a way as at once to distinguish a living organism from anything else. As this mutual determination is the characteristic mark of what is living, it cannot be ignored in the framing of fundamental working hypotheses."
The fact is that we have to regard the living organism as a new synthesis which we cannot at present analyse, and life as an activity which cannot at present be redescribed in terms of the present physical conceptions of matter and energy. And even if a living organism were artificially made, the problem would not be altered; though our conception of what we at present call inanimate might be.
Prof. Karl Pearson states the position from another point of view.
For the biologist as a scientific inquirer "the problem of whether life is or is not a mechanism is not a question of whether the same things, 'matter' and 'force,' are or are not at the back of organic and inorganic phenomena—of what is at the back of either class of sense-impressions we know absolutely nothing—but of whether the conceptual shorthand of the physicist, his ideal world of ether, atom, and molecule, will or will not also suffice to describe the biologist's perceptions." That it does not at present seems the conviction of the majority of physiologists; if it ever should it would be "purely an economy of thought; it would provide the great advantages which flow from the use of one instead of two conceptual shorthands, but it would not 'explain' life any more than the law of gravitation explains the elliptic path of a planet."
"Atom" and "molecule" and the rest are scientific concepts, not phenomenal existences, therefore even if the physicist's formulæ should fit vital phenomena—which they seem very far from doing—there would be no explanation forthcoming, for "mechanism does not explain anything."
Thus, like Spencer, we find the secret of the organism irresoluble in terms of lower categories. But we differ from him inasmuch as we believe that this admission is fatal to his formula of evolution, to his definition of life, and to the coherence of his Synthetic Philosophy.