When the moral sentiment has been explained on the principles of natural science, free-will is not likely to be regarded as presenting any serious obstacle to the same mode of treatment. By those of our national philosophers who have asserted its existence, it has generally been understood as a faculty of determining action apart from determination by motives; as a power, distinct alike from reason and from desire, which chooses between motives without itself being dependent on any motive. So crude a notion must long ago have given way before the questons of science, if there had not been a practical conviction behind it which it failed fairly to interpret. What after all, it is asked, is any faculty but an hypostatised abstraction? A faculty is no more than a possibility. Whatever happens implies no doubt a possibility of its happening. Voluntary action implies a possibility of voluntary action, just as the motion of a billiard-ball implies a possibility of that motion; but the possibility in each is determined by definite conditions. In the case of the billiard-ball these conditions, or some of them, are so obvious that we do not think of treating the possibility of the ball’s moving as a faculty inherent in the ball, and of sacrificing the ball’s motion to this faculty as its cause; although, as we know, when the causes of a motion are less apparent, the uninstructed are quite ready to ascribe it to a faculty or power in the moving body. In ascribing any voluntary action to a faculty in man, we are doing, it is said, just the same as in ascribing any particular motion to a faculty in the moving body. The fact is the particular voluntary action, which must be possible, no doubt, or it would not be done, but of which the real possibility consists in the assemblage of conditions which make up its cause. To include any faculty of action among these is merely to express our ignoranceof what they are or our unwillingness to examine them. Among them, it is true, is the wish which happens to be predominant in the agent at the moment of action; but this, too, has its definite conditions in the circumstances of the case and the motives operating on the agent. It may be owing to the character of the agent that one of these motives gets the upper hand; but his character again is only a name for an assemblage of conditions, of which it may be scarcely possible for us to completely trace the antecedents, but which we are not on that account justified in assigning to a cause that is no cause, but merely a verbal substantiation of the abstraction of our ignorance. Human freedom must be understood in some different sense from that with which our anthropologists are familiar, if it is to stand in the way of the scientific impulse to naturalise the moral man. (§6 ¶1)