Essays Upon Some Controverted Questions

by Thomas Henry Huxley

is quite possible to imagine that the mass of matter should vary according to circumstances, as we know its weight does. Moreover, the determination of the "force" which makes mass constant (if there is any intelligibility in that form of words) would not, so far as I can see, confer any more validity on the law than it has now.

There is a law of nature, so well vouched by experience, that all mankind, from pure logicians in search of examples to parish sextons in search of fees, confide in it. This is the law that "all men are mortal." It is simply a statement of the observed order of facts that all men sooner or later die. I am not acquainted with any law of nature which is more "constant and uniform" than this. But will any one tell me that death is "necessary"? Certainly there is no à priori necessity in the case, for various men have been imagined to be immortal. And I should be glad to be informed of any "necessity" that can be deduced from biological considerations. It is quite conceivable, as has recently been pointed out, that some of the lowest forms of life may be immortal, after a fashion. However this may be, I would further ask, supposing "all men are mortal" to be a real law of nature, where and what is that to which, with any propriety, the title of "compelling force" of the law can be given?

On page 69, the Duke of Argyll asserts that the law of gravitation "is a law in the sense, not merely of a rule, but of a cause." But this revival of the teaching of the Vestiges has already been examined

and disposed of; and when the Duke of Argyll states that the "observed order" which Kepler had discovered was simply a necessary consequence of the force of "gravitation," I need not recapitulate the evidence which proves such a statement to be wholly fallacious. But it may be useful to say, once more, that, at this present moment, nobody knows anything about the existence of a "force" of gravitation apart from the fact; that Newton declared the ordinary notion of such force to be inconceivable; that various attempts have been made to account for the order of facts we call gravitation, without recourse to the notion of attractive force; that, if such a force exists, it is utterly incompetent to account for Kepler's laws, without taking into the reckoning a great number of other considerations; and, finally, that all we know about the "force" of gravitation, or any other so-called "force," is that it is a name for the hypothetical cause of an observed order of facts.

Thus, when the Duke of Argyll says: "Force, ascertained according to some measure of its operation—this is indeed one of the definitions, but only one, of a scientific law" (p. 71), I reply that it is a definition which must be repudiated by every one who possesses an adequate acquaintance with either the facts, or the philosophy, of science and relegated to the limbo of pseudo-scientific fallacies. If the human mind had never entertained this notion of "force," nay, if it substituted bare invariable succession for the ordinary notion of causation, the idea of law, as the expression of a constantly-observed order, which

generates a corresponding intensity of expectation in our minds, would have exactly the same value, and play its part in real science, exactly as it does now.

It is needless to extend further the present excursus on the origin and history of modern pseudo-science. Under such high patronage as it has enjoyed, it has grown and flourished until, nowadays, it is becoming somewhat rampant. It has its weekly "Ephemerides," in which every new pseudo-scientific mare's-nest is hailed and belauded with the unconscious unfairness of ignorance; and an army of "reconcilers," enlisted in its service, whose business seems to be to mix the black of dogma and the white of science into the neutral tint of what they call liberal theology.

I remember that, not long after the publication of the Vestiges, a shrewd and sarcastic countryman of the author defined it as "cauld kail made het again." A cynic might find amusement in the reflection that, at the present time, the principles and the methods of the much-vilified Vestigiarian are being "made het again"; and are not only "echoed by the dome of St. Paul's," but thundered from the castle of Inveraray. But my turn of mind is not cynical, and I can but regret the waste of time and energy bestowed on the endeavour to deal with the most difficult problems of science, by those who have neither undergone the discipline, nor possess the information, which are indispensable to the successful issue of such an enterprise.

I have already had occasion to remark that the

Duke of Argyll's views of the conduct of controversy are different from mine; and this much-to-be-lamented discrepancy becomes yet more accentuated when the Duke reaches biological topics. Anything that was good enough for Sir Charles Lyell, in his department of study, is certainly good enough for me in mine; and I by no means demur to being pedagogically instructed about a variety of matters with which it has been the business of my life to try to acquaint myself. But the Duke of Argyll is not content with favouring me with his opinions about my own business; he also answers for mine; and, at that point, really the worm must turn. I am told that "no one knows better than Professor Huxley" a variety of things which I really do not know; and I am said to be a disciple of that "Positive Philosophy" which I have, over and over again, publicly repudiated in language which is certainly not lacking in intelligibility, whatever may be its other defects.