Surprising as this may appear to some, examination shows it to be no more than a truism, and that granted, the whole strength of the argument from adaptation, whether in the inorganic or the organic world, disappears.
To see the matter the more clearly, let us drop for a time the word "adaptation" and substitute the word "process." For that after all is what nature presents us with. We see processes and we see results. It is because we create an end for these processes that we class them as well or ill adapted to achieve it. We make a gun, and say it is ill or well made as it shoots well or ill. But whether it carries straight or not the relation of the shooting to the construction of the gun remains the same. Judging the gun merely from its construction, the product answers completely to the combination of its parts. Constructed in one way the gun cannot but shoot straight. Constructed in another way the gun cannot but shoot crookedly. And the only reason we have for calling one good and the other bad is that we desire a particular result. But the goodness or badness has nothing to do with the thing itself. Its adaptation to the end produced is as perfect in the one case as in the other. It could produce no other result than the one that actually emerges without an alteration in the means employed. A thing is what it is because it is the combination of all the forces that produce it. And to ask us to marvel at the result of a process, when the one is the product of the other is like asking us to express our surprise that twice two equal four. Twice two equal four because four is the sum of the factors, and no one dreams of praising God because they don't sometimes make four and a half. The argument from adaptations in nature is, when examined, just about as impressive as the reasoning of the curate who saw the hand of Providence in the fact that death came at the end of life instead of in the middle of it.
Adaptation is not, then, a singular fact in nature, but a universal one. It is everywhere, in the case of death as in that of life. It is the same in the case of a child born a marvel of health and beauty as in that of one born deformed and diseased. There is nothing else but adaptations of means to ends in nature, however displeasing some of them may be to us. The "harmony" which the theist perceives in nature is not the expression of "plan," it is the inevitable outcome of the properties of existence. Given matter and force, and it requires no "directive intelligence" to produce the existing order, it would indeed require a God to prevent its occurrence.
It is the same if we take the case of animal life alone. To say that animal life is adapted to its environment, and to say that animal life exists, is to say the same thing in two ways. Whether animal forms are fashioned by "divine intelligence" or not, the fact of adaptation remains; for adaptation is the essential condition of existence. And as adaptation is the condition of existence, it follows that an animal's feelings, structure, and functions will be developed in accordance with the nature of the environment. If the conditions of existence were different from what they are animal life would show corresponding modifications. But all the same we should observe the same correspondence between animal life and its surroundings. Here, again, we have a fact transformed, without the slightest warranty, into a purpose.
Now, if the theist could prove that out of a number of equally possible lines of development living beings show one fixed form, and that against the compulsion of environmental forces, he would do something to prove the probability of some sort of guidance. But that we know cannot be done. The forms of life are infinite in number. They vary within all possible limits; and always in terms of environmental conditions. In brief, what is said to occur with God, can be shown to be inevitable without him. "God" in nature is a wholly gratuitous hypothesis.
Later it will be seen that the whole basis of the argument from design is fallacious; that it proceeds along altogether wrong lines, and that the final objection to it is that it is completely irrelevant to the point at issue. For the moment, however, we proceed with a criticism of the argument as usually stated.
It must be borne in mind that what the theist desires to reach is a Creator, but it is obvious that this plea can never give us more than a mere designer working on materials that already exist. Of necessity design implies two things, difficulties to be overcome, and skill or wisdom in overcoming them. Design is an understandable thing in connection with man, because man is always occupied in overcoming the resistance of forces that exist quite independently of him, and which operate without reference to his needs or desires. But it would be absurd to assume design on the part of one for whom difficulties had no existence, or on the part of one who himself created the forces that had to be overcome, and endowed them with all the properties which made the work of design necessary. Granting the relevance of the data upon which the belief in design rests, one could only assume, with Mill, that "the author of the Cosmos worked under limitations; that he was obliged to adapt himself to conditions independent of his will, and to attain his ends by such arrangements as these conditions admitted of."
In the next place, the argument for design is an argument from analogy, and an analogy can by its very nature never give a complete demonstration. It can never offer more than a probability, more or less convincing as the analogy is more of less complete. But in the case under consideration the analogy is considerably less rather than more. Paley's classical illustration—taken almost verbatim from Malebranche, but as old otherwise as the days of Greek philosophy, where a statute took its place—was that of a watch. And the conclusion was drawn that as the parts of a watch bear obvious marks of having been made with a view to a particular end, so the animal structure and the universe as a whole bear similar marks of having been designed. It is true that of late years the Paleyan form of the argument has been disavowed by most scholarly advocates of theism, but as they immediately proceed to make use of arguments that are substantially identical with it, the repudiation does not seem of great consequence. It reminds one of a government that is compelled by the force of public opinion to openly repudiate one of its officials, and having removed him from the office in which the misdemeanour was committed, immediately appoints him to one of an increased dignity and with a larger salary.
Thus, we have Professor Fiske saying that "Paley's simile of a watch is no longer applicable to such a world as this" ("Idea of God"; p. 131), and Prof. Sorley telling us that "the age of Paley and of the Bridgewater Treatises is past" (Moral Values and the Idea of God; p. 327), and Mr. Balfour repudiating Paley as having been ruled out of court by Darwinism ("Humanism and Theism," chapter II.). But as Fiske puts the flower in the place of the watch, Sorley, the moral nature of man, and Balfour, the conditions of animal life, it is not quite clear why if the Paleyan argument is invalid, the new form is any more intellectually respectable. The essence of the Paleyan argument was the assertion of a mind behind phenomena, the workings of which could be seen in the forms of animal life. And whether we find that proof in the growth of a flower, or in the moral sense of man, or in the creation of natural conditions that impel the development of life along a certain road, the distinction is not vital. We are still finding proofs of God in the structure of the world (where otherwise, indeed, are we to find it?) and we are still depending on the supposed likeness between the works of human intelligence and natural products.
And that analogy is wholly false. The argument from design aims at proving that all things are made by a creative intelligence. It is not merely animals that are designed; they are selected as no more than striking individual examples of a general truth. Everything, if theism be true, must be ultimately due to manufacture. But the whole significance of the Paleyan argument from design is that behind the manufactured article which we recognise as such, there are other articles or other things that are not manufactured. The traveller, says Paley, who comes across a watch recognises in the relation of its parts evidences of workmanship. But he does not see in the breaking of a wave on the shore, or in the piling up of sand in the desert, or in a pebble on the beach, the same tokens of workmanship. In the very act of attempting to prove that some things are made, the theist is compelled to assume that all things are not made. He can only gain a victory at the price of confessing a defeat.