As I understand the matter, an intelligence sufficiently endowed—let us call him Laplace’s calculator—might infer the past state of the material universe from the present by a process of rigorous deduction, on accepted physical principles. But, if he carried back his investigations into a period sufficiently remote, he would find a point at which certain fundamental processes reach a theoretical limit; and, though we must believe that this condition of things had antecedents, yet infinite powers of calculation, based upon infinite knowledge of the present, could not, it seems, tell us what they were.
So much for the past. Now for the future. Here our calculator would be more successful. His prophecy, unlike his history, would not break helplessly against any impassable barrier. He could range at will over the illimitable future. But the prospect, though unbounded, would not be exhilarating. No faintest tinge of optimism would colour his anticipations. Everything that happened, good or bad, would subtract something from the lessening store of useful energy, till a time arrived when nothing could happen any more, and the universe, frozen into eternal repose, would for ever be as if it were not.
Do our ideas of material evolution, thus corrected and supplemented, lend themselves easily to the argument from design? I hardly think so. It is true that in retrospect we can ideally reach a limit which no calculations, based upon physical laws, will permit us to overpass, and that where (what in old-fashioned language were called) “secondary causes” fail us, a First Cause may plausibly be invoked; but, if we gaze forward instead of backward, the physical course of nature does not merely fail to indicate design, it seems loudly to proclaim its absence. A world where all energy suffers inevitable degradation, considered by itself, appears atheistic on the face of it: nor can even life consciousness or thought redeem it, if they, too, are doomed to perish when further transformations of energy become impossible.
It is not, therefore, on any general survey of material nature that, in the present state of our knowledge, we can base the argument from “design.” Nor is this the foundation on which those who use the argument have chiefly built. They have always sought for proofs of contrivance rather among the living than among the dead. In the intricate adjustment of different parts of an organism to the interests of the whole; in the adaptation of that whole to its environment, they found the evidence they required. Arrangements which so irresistibly suggested purpose could not (they thought) be reasonably attributed to chance.
This argument possessed immense force in what was, comparatively speaking, the infancy of biology. Has that force been lessened by the growth of knowledge? Yes and No. If we consider organic adaptations and adjustments in themselves, scientific discovery has increased a thousand-fold our sense of their exquisite nicety and their amazing complexity. I take it as certain that, had no such theory as Natural Selection been devised, nothing would have persuaded mankind that the organic world came into being unguided by intelligence. Chance, whatever chance may mean, would never have been accepted as a solution. Agnosticism would have been scouted as stupidity.
All this has been changed, as every one knows, by Darwin. But what exactly was it that, in this connection, Darwin did? He is justly regarded as the greatest among the founders of the doctrine of organic evolution; but there is nothing in the mere idea of organic evolution which is incongruous with design. On the contrary, it almost suggests guidance, it has all the appearance of a plan. Why, then, has Natural Selection been supposed to shake teleology to its foundation?
The reason, of course, is that though the fact of Selection does not make it harder to believe in design, it makes it easier to believe in accident; and, as design and accident are the two mutually exclusive alternatives between which the argument from design requires us to choose, this comes to the same thing. Before Darwin’s great discovery those who denied the existence of a Contriver were hard put to it to explain the appearance of contrivance. Darwin, within certain limits and on certain suppositions, provided an explanation. He showed how the most complicated and purposeful organs, if only they were useful to the species, might gradually arise out of random variations, continuously weeded by an unthinking process of elimination. Assume the existence of living organisms, however simple, let them multiply enough and vary enough, let their variations be heritable, then, if sufficient time be granted, all the rest will follow. In these conditions, and out of this material, blind causation will adapt means to ends with a wealth of ingenuity which we not only cannot equal, but which we are barely beginning to comprehend.[2]
The theory of selection thus destroys much of the foundation on which, a hundred years ago, the argument from design was based. What does it leave untouched?
It leaves untouched all that can be inferred from the existence of the conditions which make organic evolution possible: matter which lives, multiplies, and varies; an environment which possesses the marvellously complex constitution required to make these processes possible. Selection may modify these conditions, but it cannot start them. It may modify the manner in which multiplication is secured; it may modify the lines which variations follow; it may enable organic species to adapt their powers to their environment, and (within narrow limits) their environment to their powers. But it cannot produce either the original environment or the original living matter. These must be due either to luck or to contrivance; and, if they be due to luck, the luck (we must own) is great. How great we cannot say. We cannot measure the improbability of a fortuitous arrangement of molecules producing not merely living matter, but living matter of the right kind, living matter on which selection can act. Here, indeed, Laplace’s calculator might conceivably help us. But suppose him to have done so, suppose him to have measured the odds against the accidental emergence of the desired brand of protoplasm, how are we to compare this probability with its assumed alternative—intelligent design? Here, I think, even Laplace’s calculator would fail us; for he is only at home in a material world governed by mechanical and physical laws. He has no principles which would enable him to make exhaustive inferences about a world in which other elements are included: and such a world is ours.
For a Greek philosopher to assert that the world is material was legitimate enough. He was in search of a universal principle; and if he found it in matter we need neither wonder nor criticise. After all, matter lies round us on every side; we are immersed in it; we are largely dependent on it. It may well seem but a small step further, and a very natural one, to treat it as the essence of all that is.