Evolution

by F. B. Jevons

What we have said with regard to science applies also of necessity to Evolution. If Evolution is simply the continual redistribution of matter and motion, if matter and motion are the only things subject to evolution, then consciousness and conscience are not subject to evolution. On the other hand, if they too have had and are having their evolution, then the redistribution of matter and motion does not sum up the process of evolution, and is not a correct statement of the process. If it were an induction drawn from a consideration of all the facts of evolution, it would cover them all. But it does not: it excludes a large class of important facts, because their exclusion is demanded in the interests of a particular metaphysical theory—the mechanical theory. It implies that the operation of evolution is confined to a limited set of facts. If the implication is false, then evolution is a bigger thing than the mere redistribution of matter and motion.

The way in which it is usually attempted to force the mechanical theory to square with the facts, or rather to cut the facts to fit the theory, is to point to the connection between the mind and the brain, and to proclaim the consequent dependence of mind on matter. Now, that there is a connection between mind and brain is certain. What the connection is exactly is as yet uncertain. But the fact that two things co-exist, are connected with one another and vary together, does not prove that the one thing is the other. On the contrary, it postulates that the two things, though related, are different. The mechanical theory either commits the fallacy of mistaking connected things for identical things, or it fails to prove the very thing necessary for its justification, viz. that thoughts, emotions, etc., are things occupying space and moving in space. The chemical and physiological changes which take place in the brain are movements in space. But it does not follow that the corresponding pains or ideas float about in the air or move from one point in space to another.

Further, as a metaphysical theory, this identification of matter with mind is a double-edged weapon: it cuts both ways: if mind is matter, matter is mind; if mind is thinking matter, then matter is latent thought; and thought is consequently exhibited not as being the last product of evolution, but as a factor in it from the beginning. But this identity of mind and matter is a purely metaphysical speculation: it is a conjecture to explain how it is that two phenomena can co-exist in the way in which they are observed to do. Such conjectures science does not require: she does not undertake to explain why things are, but to describe—if possible with mathematical exactness—the order of their sequence or co-existence. This function science can discharge equally well whether the changes of consciousness are or are not supposed to be movements in space. Metaphysicians may argue the point; in the meantime science is describing and formulating the laws of mind and endeavouring to correlate the changes of consciousness with the physical changes of the brain and the nervous system. The mechanical theory neither helps nor hinders science in her work.

But science does throw some difficulties in the way of the mechanical theory; or, rather, the facts of science refuse to fit into the theory. If the stream of consciousness is nothing but a series of physiological and chemical changes, the laws of the one ought to be identical with the laws of the other, and both with the laws of mechanics, on the mechanical theory. But they are not. Those concise descriptions of mental phenomena which constitute the laws of psychology ought to coincide with those other concise descriptions of fact which constitute the laws of chemistry, if the facts described by the two sciences are the same. But the two sets of laws have, to say the least, more differences than resemblances.

This brings us to our second point. Our first point was that if the concise description of evolution, which sums it up as the process by which matter is continually redistributed in space, is to be proved to be true, it must be shown that movements in space are the only events which we know to take place. Our second point is that, unless it can be shown that mechanical laws are the only laws at work in the universe, this description of evolution does not find room for the whole working of the process of evolution.

Whether the only laws in the universe are mechanical laws is primarily a question of fact; and on the facts, as known to us at present, the answer to the question is a decided negative. The laws of psychology and of ethics are neither identical with nor have they been deduced from any physical laws. As a hypothesis designed to explain the way in which the world works, the redistribution of matter and motion neither includes nor accounts for those laws which are of most importance to man.

This appeal to the facts which are actually known is, however, often conceived to be in reality an appeal to our ignorance: mental laws have not as yet been shown to be deducible from physical laws, but they may be. So, too, the fact that no attempt to extend the gravitation formula from astronomy to any other department of science has yet succeeded, is no proof that it never will be so extended. Neither, we may remark, does it constitute any presumption that it will. Are there, then, any other grounds for presuming that mental law may yet be shown to be merely a case of some physical law? To some minds there seem to be grounds for presuming that it not only may, but must. However great our ignorance of the details of the process of evolution, there are certain broad facts which are beyond dispute. It is indisputable that there was a period in the history of the earth when there was no life upon it; that the elements which constitute living matter are themselves lifeless; that consciousness is correlated somehow with those organic compounds, the elements of which are inorganic. These facts together constitute an irresistible presumption that ultimately mind and matter must obey the same laws.

But this is not the desired conclusion. The conclusion desired is that mind must obey matter's laws. The fact that mind and matter obey the same ultimate laws is a different thing, and rather indicates that even the redistribution of matter and motion requires ultimately some other explanation than merely mechanical laws afford. To the religious mind it is quite intelligible that mind and matter should obey the same laws—God's laws.

It may be said, however, that we have not done full justice to the presumption raised by the broad facts of evolution. When there was no life upon the earth, the only laws in operation must have been physical laws, and consequently the laws of life and consciousness must have been produced by the laws of matter.

Now, this argument in effect amounts to a denial of any difference between the mechanical composition and the chemical combination of bodies. Bodies when mechanically compounded continue to follow the same laws as they obey when uncompounded, and their conjoint action can be deduced and foretold from the laws to which they are subject in their separate state: "Whatever would have happened in consequence of each cause taken by itself happens when they are together, and we have only to cast up the results."[17] With chemical combination the case is quite different: the chemical compound exhibits properties and behaves in ways which are quite different from the properties and behaviour of its elements, and could not be foretold from any observation of them. Water, which is a combination of oxygen and hydrogen, exhibits no trace of the properties of either. "If this be true of chemical combinations, it is still more true of those far more complex combinations of elements which constitute organised bodies, and in which those extraordinary new uniformities arise, which are called the laws of life. All organised bodies are composed of parts similar to those composing inorganic nature, and which have even themselves existed in an inorganic state; but the phenomena of life, which result from the juxtaposition of those parts in a certain manner, bear no analogy to any of the effects which would be produced by the action of the component substance considered as mere physical agents.... The tongue, for instance, is, like all other parts of the animal frame, composed of gelatine, fibrin, and other products of the chemistry of digestion, but from no knowledge of the properties of those substances could we ever predict that it could taste, unless gelatine or fibrin could themselves taste; for no elementary fact can be in the conclusion which was not in the premises."[18]