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ology is a reduction of vital phenomena to general physical laws, and ultimately to the fundamental laws of mechanics;" and Haeckel tells us that “all natural phenomena without exception, from the motions of the celestial bodies to the growth of plants and the consciousness of men ..... are ultimately to be reduced to atomic mechanics."
Many, if not most, of the scientific men of our day strongly favor a mechanical explanation of nature, and treat with disfavor, not to say contempt, the conception of a distinct kind of energy or a “ VITAL FORCE"-a conception which has been maintained by a school of physiologists called on that account“ vitalists."
Now it is surely not to be supposed that this preference for "mechanism" by so many distinguished men of science can be due to any mere prejudice on their part, or that there are not some good and substantial reasons why they should favor it, and yet it is hard to suppose that the common sense of mankind, which has ever opposed the mechanical view, can be entirely due to a mere delusion either, and have no solid support from reason !
Let us first for a moment consider what is the aim and end of all physical science. Surely it is to understand the coexistences and successions of natural phenomena in such a way that they can not only be arranged in convenient groups suitable for the limited powers of the human intellect to grasp, but also serve as a basis of scientific prediction-while the coming true of “predictions" which men of science feel justified in making affords a strong ground for believing that the operations which served as a basis for such fulfilled predictions were themselves true.
Thus, as regards the science of astronomy, who does not now see that our conceptions of the motions of the heavenly bodies have been greatly facilitated by the discovery of the law of gravitation ? and who does not perceive in the verification of scientific prophecy, by the discovery of the planet Neptune, a signal triumph of modern astronomical science?
Nevertheless, the fulfilment of predictions alone will not always suffice to prove the absolute truth of the views upon which they are supposed to be based, or else the prediction of eclipses by astronomers who followed the Ptolemaic system would have proved the truth of that erroneous theory.
Bearing in mind, however, the aim and end of physical science, let us next glance at the only means which it is in the power of scientific men to use. These means are the employment of present sense-impressions, together with the reproduction in the investigation of groups of past sense-impressions.
All our knowledge is called forth by the play of surrounding nature upon our sense-organs; nor can we imagine anything which
we have not previously had sensuous experience of—at least in its elements or component parts.
Again, there is a quality of distinctness and vividness in our sense-impressions. How vague, for example, is our imagination of a perfume, compared with our imagination of a visible triangular figure, or of a cube, or of a ball, held in the hand ?
It is especially what is visible and tangible that comes home most readily to the imagination; vague internal sensations are always described by us in terms of sight or touch. We speak of a"
“gnawing" pain, a “sharp" pain, like a knife, a “rough” taste, and even a "bright" intellect, and a "hard" heart.
Now, the “explanation" of any phenomenon may be its reference to the causes which produce it; but its "explanation” is very often nothing more than the assigning of some new or unfamiliar object to a class of objects which has already become familiar; and our minds are so formed that they feel an almost inevitable satisfaction in the reference of some object or action, difficult or impossible to imagine, to a class of objects or actions easy to imagine, and this whether or not such reference, when closely examined, turns out to be really justifiable, and therefore truly satisfactory.
Now there is nothing so easy for us to imagine as the motions of solid bodies, phenomena which appeal both to sight and touch. Thus it is that (apart from scientific utilities we shall shortly refer to) “heat," "light,” “chemical phenomena,” the action of nerves and of brain cells, are apt to appear easier to understand, and to be more or less "explained,” when they are spoken of as “MODES OF MOTION."
Nevertheless, such an explanation of the action of living beings is, as we have said, shocking to common sense, and therefore, as has just been mentioned, another force was invented to account for thern, and the actions of living beings have been explained as being due to the energizing within them of a “Vital Force.”
But the doctrine of the existence of any such force has been more and more successfully opposed by men of science on the ground that (1) living beings are not isolated phenomena in nature, but are affected by and react upon all physical forces; (2) that no distinct evidence is forthcoming of the existence of any such “vital force;" and (3) that while the use of such a conception in no way furthers the ends of science, the mechanical conception of nature aids in the discovery of natural laws, and has powerfully helped on the progress of science.
And it is true that living beings are far indeed from being isolated; for the life of each largely consists of an interplay between what we consider its own body and environing nature. So intimate, in fact, is the connection between each of us and his environ
ment, that it is even difficult to determine, in minute detail, the line of separation between the two. Food, even when swallowed, is not yet “the tissue.” When digested and entering the absorbents which convey it to the bloodvessels which carry it to the intimate tissues of the body, who can say exactly how soon the foreign body becomes the living being, or precisely when and where it is transformed into our very substance? It is the same with the streams of air carrying inwards the life-sustaining oxygen and outwards the deleterious vapors. By such agencies the outer world blends with us and we with it. Far from finding any such indubitable evidence of the existence of a “vital force," as we have of those phenomena we speak of as “heat,"" motion,” and “light," each living organism thus viewed purely from the standpoint of physical science seems, in the words of a distinguished German philosopher, Lotze, only as a place in space where the matter, the forces and the motions of the general course of Nature meet each other in relations favorable for the production of vital phenomena. These phenomena excite our admiration, as do the phenomena of heat and pictorial transmission in that part of space near a lens which is called its “focus." Yet the phenomena of the focus are not explained by any peculiar force common to all “foci” (and so comparable with the agency of " vital force "), but are scientifically accounted for by light and the agencies of media of different densities, through which it is said to be transmitted.
The life of an organism may be compared (from the physical science point of view) to the quiet light of a wax candle which seems, to the uninstructed observer, to be the simple action of what he calls “fire," while to the man of science it is a most complicated series of changes, chemical and physical-oxygenation, decomposition, the formation of water, capillary attraction, etc., etc., all of which must be taken together to explain by their diverse simultaneous activities, the apparently simple effect.
But not only is the existence of a diffused “vital force" not demonstrable, and not only do men of science yield to a general tendency of human nature in imaging forth the world's activities generally, in terins of moving matter; but they very properly advocate the use of a means which experience has shown them to be most efficacious for their own legitimate end, which is the progress of physical science. The wonderful discoveries which modern research has made, have been made, not by investigating the ebb and flow of an imaginary " vital force," but by the application to the study of living nature of the previously ascertained laws of chemistry and physics. The discovered laws of the phenomena of digestion, of respiration, of the circulation of the nutritive fluids, etc., are all instances of the successful application of
physics to the investigation of the phenomena of life. To that fruitful source alone we have also to look for the remedies of the physical ills of bodily life, for the perfecting of the trained skill of the physician, as well as, and no less than, that of the more obviously mechanical art of surgery.
Physical science can repose upon and appeal to nothing but things evident to the senses. It is thus compelled to make use of a mechanical imagination of nature, and no blame can therefore attach to physicists who regard this as their practical ideal, and attend exclusively to the physical forces, disregarding that discredited figment termed “vital force.”
Should we, then, really accept the mechanical theory of the universe as an ABSOLUTE TRUTH ? and are we to regard the world of animals and plants as presenting no really essential difference from that of the inorganic world ?
We are far from thinking men are compelled to do this, and we will endeavor briefly to give our reasons why we think men are not so compelled
Physical science is great, but it is not everything; and it cannot, by its very nature, be supreme. It essentially reposes upon our sense-perceptions, but it is not "sense,” but “intellect” which is and must be supreme in us. It is not "sense,” but “thought," which tells us that we have sense-perceptions at all, and which criticises them and makes use of them. They are the indispensable servants of our intellect, without them it cannot move a step, but they are none the less its servants. Though we can have no imagination, and therefore no thoughts, till our minds are roused to activity by the action of the world about us on our sense-organs; though we can imagine nothing of the elements of which we have not had sensuous experience, nevertheless we gain through the ministry of sense that which is not sensuous, but which regulates our every thought and rational action. The great principle, called that of contradiction, which lies at the root of our intellectual life-the principle that nothing can, at the same time, “be” and “ not be," may be taken as the type of conceptions which are gained through sense, but are not of sense.
Reason in man is supreme; and it relates to those first principles which have been recognized by one of our greatest living physicists as ""
underlying all physical science." Great, therefore, as may be the utility of a mechanical view of nature, fully justified as men of science are in making use of it, and advocating its use for their own ends, it by no means follows that we should regard this useful working hypothesis as the very truth! We should or should not so regard it according as it may appear when viewed,
not in the light of physical science, but in that of philosophy, which is the judge of physical science.
Here, then, we may return, for a moment, to the consideration of nature as the arena for the play of forces, whether“ physical” or “vital.”
It is, as we know, the scientific fashion of the day (and a practically useful fashion) to regard the phenomena of living beings as “physical,” and to also consider the various physical forces, heat, light, chemical affinity, etc., as so many modes of motion.
But when we raise ourselves above the horizon of physical science to the broader outlook of philosophy, can we then regard this practical reduction of all things to “motion " as really an explanation ?
We have freely conceded that “vital force" is a figment, but what are we to say of heat, light, and motion also ? Are they realities?
In fact, they are in the mselves nothing more than abstractions of the mind. There is no such thing as "heat," or as “motion; though, of course, there are numberless warm bodies of different temperatures, while as to the quality “moving,” nothing, so far as we know, is absolutely at rest. But they are commonly spoken of as if they were not mere qualities of bodies, but actual substances, which may pass from one body into another and mutually transform themselves. To explain the phenomena of living beings, then, by "mechanical motion,” however practically convenient for the investigation of physical science, is, from the point of view of pure reason, a philosophical absurdity. It is an attempt to explain them by a nonentity-a mental abstraction from a certain quality found in things. Moreover, as living creatures make known to us various different" qualities,” to attempt to explain them all by different quantities of one only quality is an attempt to extract the category of QUALITY out of the category of QUANTITY, which every one at all versed in philosophy will recognize as a selfevident absurdity.
Please recollect that we are in no way objecting to the use of such conceptions as that of the “ transformation of force” for the purpose of aiding calculations and for general advance in physical science; we only object to the incautious use of such language as may lead persons to believe that “forces " are substances, or to the notion that such conceptions are really profound truths; as if we really knew physical motion better than we do thought or will.
What essential distinction, then, does there remain to draw between living beings and beings devoid of life? There remains that distinction which was drawn more than two thousand two hundred years ago by the greatest of philosophers, and which has the advantage of agreeing with what common sense tells us to-day.