They not only say that they are right as to what good is, but they endeavour to prove that other people who say that it is something else, are wrong. One, for instance, will affirm that good is pleasure, another, perhaps, that good is that which is desired; and each of these will argue eagerly to prove that the other is wrong. But how is that possible? One of them says that good is nothing but the object of desire, and at the same time tries to prove that it is not pleasure. But from his first assertion, that good just means the object of desire, one of two things must follow as regards his proof:
(1) He may be trying to prove that the object of desire is not pleasure. But, if this be all, where is his Ethics? The position he is maintaining is merely a psychological one. Desire is something which occurs in our minds, and pleasure is something else which so occurs; and our would-be ethical philosopher is merely holding that the latter is not the object of the former. But what has that to do with the question in dispute? His opponent held the ethical proposition that pleasure was the good, and although he should prove a million times over the psychological proposition that pleasure is not the object of desire, he is no nearer proving his opponent to be wrong. The position is like this. One man says a triangle is a circle: another replies, ‘A triangle is a straight line, and I will prove to you that I am right: for’ (this is the only argument) ‘a straight line is not a circle.’ ‘That is quite true,’ the other may reply; ‘but nevertheless a triangle is a circle, and you have said nothing whatever to prove the contrary. What is proved is that one of us is wrong, for we agree that a triangle cannot be both a straight line and a circle: but which is wrong, there can be no earthly means of proving, since you define triangle as straight line and I define it as circle.’—Well, that is one alternative which any naturalistic Ethics has to face; if good is defined as something else, then it is impossible either to prove that any other definition is wrong or even to deny such definition.
(2) The other alternative will scarcely be more welcome. It is that the discussion is after all a verbal one. When A says ‘Good means pleasant’ and B says ‘Good means desired,’ they may merely wish to assert that most people have used the word
