The part of ethics which is concerned, not with conduct, but with the meaning of good and bad, and the things that are intrinsically good and bad, is plainly quite independent of freewill. Causality belongs to the description ofthe existing world, and we saw that no inference can be drawn from what exists to what is good. Whether, then, causality holds always, sometimes, or never is a question wholly irrelevant in the consideration of intrinsic goods and evils. But when we come to conduct and the notion of ought, we cannot be sure that determinism makes no difference. For we saw that the objectively right action may be defined as that one which, of all that are possible under the circumstances, will probably on the whole have the best consequences. The action which is objectively right must therefore be in some sense possible. But if determinism is true, there is a sense in which no action is possible except the one actually performed. Hence, if the two senses of possibility are the same, the action actually performed is always objectively right; for it is the only possible action, and therefore there is no other possible action which would have better results. There is here, I think, a real difficulty. But let us consider the various kinds of possibility which may be meant. (§ 26 ¶ 1)

In order that an act may be a possible act, it must be physically possible to perform, it must be possible to think of, and it must be possible to choose if we think of it. Physical possibility, to begin with, is obviously necessary. There are circumstances under which I might do a great deal of good by running from Oxford to London in five minutes. But I should not be called unwise, or guilty of an objectively wrong act, for omitting to do so. We may define an act as physically possible when it will occur if I will it. Acts for which this condition fails are not to be taken account of in estimating rightness or wrongness. (§ 26 ¶ 2)