(1) That the criterion of Good is a simple infallible instinct. To which it is replied that there appear to be many such 'instincts' conflicting among themselves.
(2) That the criterion of Good is the course of Nature; Good being defined as the end to which Nature is tending. To which it is replied that such a judgment is as a priori and unbased as any other, and as much open to dispute.
It is then urged that if we reject the proposed criterion, we can have no scientific basis for Ethics; which leads to a brief discussion of the nature of Science, and the applicability of its methods to Ethics.
(3) That the criterion of Good is current convention. To which it is replied, that conventions are always changing, and that the moral reformer is precisely the man who disputes those which are current. Especially, it is urged that our own conventions are, in fact, vigorously challenged, e.g. by Nietzsche.
(4) That the criterion of Good is Pleasure, or the "greatest happiness of the greatest number." To which it is replied:
(a) That this view is not, as is commonly urged, in accordance with 'common sense.'
(b) That either Pleasure must be taken in the simplest and narrowest sense; in which case it is palpably inadequate as a criterion of Good; or its meaning must be so widely extended that the term Pleasure becomes as indefinite as the term Good.
(c) That if the criterion of Pleasure were to be fairly applied, it would lead to results that would shock those who profess to adopt it.
III. These methods of determining Good having been set aside, it is suggested that it is only by 'interrogating experience' that we can discover, tentatively, what things are good.
To this it is objected, that perhaps all our ideas derived from experience are false, and that the only method of determining Good would be metaphysical, and a priori. In reply, the bare possibility of such a method is admitted; but it is urged that no one really believes that all our opinions derived from experience are false, and that such a belief, if held, would deprive life of all ethical significance and worth.