Evolution

by F. B. Jevons

Let us imagine a game of chess in course of being played by invisible players in presence of a scientific philosopher who knows nothing about the game—or who assumes that he knows nothing—except what his senses tell him.

What he sees will be simply material chess-men moving in space. He may either consider them to be merely sense-phenomena, merely affections or modifications of his sense of sight and touch, or he may consider them to be real, material things. In either case he makes an assumption. The latter assumption leaves it quite an open question whether the reality is something insentient or is the expression of conscious will. The former precludes the question, i.e. assumes that there is neither conscious will nor insentient matter behind them.

But in neither assumption is there anything to prevent the philosopher in question from studying the movements of the chess-men and the way in which at every move or moment they are redistributed. At first their movements would probably be rather bewildering; but in course of time he would note, we may assume, that Black never moved unless White had previously moved, and that any movement of White was followed by one on the part of Black. He might therefore be tempted to lay it down as a rule that Black never moved unless White moved first—that an effect never occurred without a cause; and that a movement of White was always followed by a move on the part of Black—that a cause was always followed by its effect. But if he yielded to this temptation he would be making an assumption, for—inasmuch as he professes to know nothing to begin with—he does not know that the pieces always will move in this way; he only knows (assuming that memory is not a mere delusion, as it may be, for anything he knows) that they have moved thus, not that they always will move thus. He may, however, assume that they will continue to move in that way. But with every fresh assumption he becomes less and less of an agnostic. He may, indeed, if he likes, further assume, not only that the pieces will move in this way, but that they must. This assumption does not, indeed, seem necessary; for if we know (or assume that we know) that they will follow this course, it seems superfluous to say that they must.

It seems well, therefore, to try to see on what principle we are to make our assumptions. It is an ancient rule, and one followed by science, to make as few as possible—that is to say, the fewest that will suffice for the purpose in hand. If, therefore, the purpose of our study of the chess-board is merely to find out how and according to what rules the pieces actually do move, have moved, and will move, it seems sufficient to assume that they will move as they have done, not that they must. If, on the other hand, we want to know why they move in the way that we assume them to move, then the assumption that they do so because they must is certainly in form legitimate, though it may or may not be the right one in fact.

Some people refuse to discuss such questions as "Why this universe?" "What is the reason of this unintelligible world?" on the ground that they cannot be answered except by making assumptions which cannot be proved.

But is that really a good reason for refusing? If it is, then none of the questions which science exists to answer can be discussed, for they also can only be answered by assuming, without proof or possibility of proof, that Nature is uniform, that the chess-men will continue to move as they have done.

Be this as it may, our philosopher, if he assumes that the course of Nature is not only uniform, but necessary, is making an assumption which is not required for the purposes of science, though it may be for his philosophy. It is, as we have said, quite legitimate for him to make the assumption for philosophical purposes, and to adhere to its logical consequences. But in the interests of clearness of thought it should be recognised that those consequences flow from it, and not from any of the assumptions necessary for the purposes of science. He will be able to show on this assumption that there is nothing in the history of the universe, or in the facts of science, to countenance the idea that the universe is the expression of self-determining will. We only wish to point out that this conclusion, even if true, is not an inference from the facts of science, but from the initial assumption that nothing which takes place in Nature is the result of free will.

To say, "Science does not find it necessary to assume the existence of self-determining will, neither therefore will I assume it," is true, but is only half the truth. Science does not find it necessary to assume the non-existence of self-determining will. But the philosopher who explains the facts of Nature on the hypothesis that they happen of necessity, does assume that self-determining will is non-existent. It is therefore quite natural that the history of the universe and the facts of science, interpreted in this way, should lend no countenance to the opposite theory.

The history of the universe may also be interpreted as a manifestation of the Divine will, the process of evolution as a progressive revelation; and if any be tempted to say with a sigh, "Ah! but it all requires us to believe that there is a God, to begin with," let them reflect that the other interpretation cannot even begin without the assumption that there is no God.

But to return to our chess-men. A closer study of the game would reveal—in addition to the invariable sequence of Black, White, Black—the fact that the various pieces had various properties and moved in various ways, some only one square at a time, some the whole length of the board; some diagonally, some parallel to the sides of the board. Further, our philosopher would observe that each piece when it moved tended to move according to its own laws: in the absence of counteracting causes, e.g. unless some other piece blocked the way, a bishop tended to move diagonally the whole length of the board. As a man of science, he would state these observed uniformities in the hypothetical form rightly adopted by science: if a castle moves it tends to move in such and such a way. Thus eventually he would be able to foretell, whenever any piece began to move, what direction it tended, in the absence of counteracting causes, to take. He might not, indeed, be able to say beforehand which of White's pieces would move in reply to Black, but his knowledge of the game would eventually become so scientific that he would be prepared for most contingencies, i.e. be able to say approximately where any piece would move if it did move. That knowledge could be attained without making any assumption as to whether free-will or necessity was the motive force expressed in the game; and it would be equally valid whichever of the two assumptions he chose to make. His science would have nothing to hope or fear from either assumption.