But before proceeding to this discussion I propose, first, to deal with the third kind of ethical question—the quesiton: What ought we to do? (§ 88 ¶ 1)

The answering of this question constitutes the third great division of ethical enquiry; and its nature was briefly explained in Chap. I (§§ 15—17). It introduces into Ethics, as was there pointed out, an entirely new question—the question what things are related as causes to that which is good in itself; and this question can only be answered by an entirely new method—the method of empirical investigation; by means of which causes are discovered in the other sciences. To ask what kind of actions we ought to perform, or what kind of conduct is right, is to ask what kind of effects such action and conduct will produce. Not a single question in practical Ethics can be answered except by a causal generalisation. All such questions do, indeed, also involve an ethical judgment proper—the judgment that certain effects are better, in themselves, than others. But they do assert that these better things are effects—are causally connected with the actions in question. Every judgment in practical Ethics may be reduced to the form: This is a cause of that good thing. (§ 88 ¶ 2)