The adaptation of means to ends is an evident sign of an intelligent cause. Nature offers instances of the adaptation of means to ends. Hence it follows that nature is the work of an intelligent cause. This cause must be God.
Before addressing the substance of our argument a word must be said on the significance of the word 'means.' A cause is only considered a means to a particular result, when its action has been determined in view of that result as an end. If an effect follows from the operation of a cause in such a manner that there is no need to suppose a direct reference of the cause to its production, we don't regard the latter as a means. Thus, if a high wind results in the fall of some trees, we don't speak of it as a means to the fall of these trees. On the other hand, works of human industry are as a rule means. The bit in the horse's mouth is a means to its control, the train engine is a means to the propulsion of freight cars. We affirm, then, that the adaptation of means to ends is an evident sign of an intelligent cause. The statement hardly calls for formal proof. Means, as we have said, are such in virtue of being determined in view of the end. They are directed to it, and apart from their relation to it, it wouldn't be an end. Now only an intelligence has power to apprehend the relation of one thing to another—to understand the proportion of a means to its end— the 'reason why' of this means. It follows that only an intelligent cause can set one thing in relation to another as its end—can employ it as a means. Wherever, therefore, we find the adaptation of means to an end, we have evidence of a directing intelligence. Only an intelligent cause can employ a thing as a means, which is illustrated in the familiar definition of man as a tool-using being. The employment of instruments supposes intelligence. Since man alone among all creatures in creation possesses true intelligence, he alone knows how to fashion and make use of tools. He is able to manufacture and use tools because he is rational. The same result can be reached in another way. If the means are really determined by the end, it is certain that this latter must have some sort of being. A nonentity couldn't exert a determining influence on the physical causes. If the house about to be built actually determines the cutting of the timber and the shaping of the stones which are to form it, that house in some manner actually exists. But ex hypothesi it doesn't yet exist in the real order. Thus, in so far as it determines the means, its being must be in the ideal order. Now nature does in fact display countless instances of the adaptation of means to ends. It follows, therefore, that the cause of nature is a being endowed with knowledge. It is evident that pantheism, such as that of the philosopher Hegel, which holds that there is but one Absolute Substance, of which all finite things are manifestations, but which only attains full self-consciousness in the human spirit, must of necessity reject our conclusion. It has no place for a prior efficient cause to whose intelligence the adaptation of means to ends in the realm of nature is due. Considering the influence that Hegel's system exerts even today in some circles, it is something we must address. He strongly believed that finality was present throughout the whole world process, but was emphatic in denying that there is any need to refer it to a separate efficient cause. According to Hegel, the finality of the world is immanent. It may be best understood from what we see take place in a living organism. There the idea is present from the beginning, governing the whole process of development, until it attains its full realization. The goal is not reached through means which are external to the organism; but all its parts are reciprocally ends and means to each other, and all in combination work for the final end in view. So it is in the universe. The universe passes on to its own realization. Cause, means and end aren't separate things as in the works of human industry. The end realizes itself. This explanation of the finality in nature doesn't meet the test of critical examination. There are no grounds whatsoever for saying that immanent finality dispenses with the action of an intelligent efficient cause. It is true that in this case the principle of development exists within the substance, determining all its parts in such a way that they contribute to each other's perfection and cooperate to the ultimate result. But how is this determination to be explained? It is an error to say that the end as actually realized is operative throughout the process. The process takes place in time, and until it is past and gone, the end as actually realized has no existence. What doesn't exist certainly can't operate! It would be like saying that the ultimate form of a statue was operative in bringing itself into being. We can't deny that the final result does in some manner determine the contributory agents to its own production, but there is no possible way in which it can do this, except in so far as it has a prior ideal existence in an intelligent efficient cause. Yet some seem to imply that an immanent activity is in some way exclusive of a distinct efficient cause; that this latter is only to be supposed when we're dealing with means directed to an external end. This is a mere assumption. It is true that man can't give life to his productions and endow them with the power of self-development, but no impossibility is involved in the idea of such efficiency. The Hegelian theory involves another fallacy, which we're just briefly going to mention. It views the world as though it were an organism, endowed with a life of its own, and actuated by a principle of internal evolution. This is a thoroughly misleading concept. The universe is built up out of many substances. Undoubtedly it possesses a unity of its own, but this isn't the unity of a single substance, it is a unity of order, all the diverse substances being so related to each as to form an organized whole.
Now let's take a look at the other premise of our argument, and ask: Does nature really provide examples of the adaptation of means to ends? This fact might seem obvious, since we have so many examples of design in things around us. After all, what could be more obvious than that the ear is fashioned to hear, the eye to see, and the hand to work, just to name a few examples? Yet it is maintained by Atheistic Naturalists that we're mistaken in attributing any finality to nature. They claim the natural order is sufficiently explained by efficient causality alone. The physical agents of which the universe is formed have operated each after its kind, and in so doing have realized certain results. But this action wasn't guided by a set aim, nor was it determined in view of the attainment of a particular end. We agree that man acts in this way, since man is conscious. He proposes an end to himself, and directs his action towards its realization. But we have no reason to apply this concept to the works of nature. The analogy between human industry and the action of physical causes is invalid, and instances adduced in proof of finality have again and again proven wrong. Wheat doesn't grow so man can have bread, but man makes and eats bread because there is such a thing as wheat. The bird doesn't possess wings in order for it to fly. It flies because physical causes have given it wings.
It should be noted that there is a significant difference between these two examples. In the one case we're concerned with external finality. In the other case we're concerned with internal—the actual operation of the organ in question. It is plain that in nature internal finality is far clearer than external. It is frequently rash to assume, because a substance is useful for a particular external purpose, that it exists for that end. We can't affirm that the papyrus plant exists so that ancient Egyptians would have paper. But where internal finality is concerned there isn't the same difficulty. Our argument rests primarily on internal finality. Our first piece of evidence that there are ends in nature is drawn from the undeniable fact that our intellect recognizes, and can't avoid recognizing, finality in nature's operations. Finality is one of those features of reality which form the proper object of the intellect. It falls within the scope of that faculty to apprehend it. And if, after due consideration, it judges a given effect to be the final cause of certain antecedent phenomena, it isn't mistaken. The object of the intellect is being and those notions which are immediately connected with being, and among these we included the notion of finality. Just as, where the requisite conditions are present, the mind pronounces infallibly of a given antecedent that it is an efficient cause, so it can affirm of a given consequent that it is a final cause.