As I have said, I feel some doubts myself whether they are or not: it does not seem to me to be a matter to dogmatize upon. But I am strongly inclined to think that they are not merely psychological; that Moral Philosophy and Ethics are not mere departments of Psychology. In favour of the view that the two ideas in question are merely psychological, there is, so far as I am aware, nothing whatever to be said, except that so many philosophers have been absolutely convinced that they are. None of them seem to me to have succeeded in bringing forward a single argument in favour of their view. And against the view that they are, there seem to me to be some quite definite arguments, though I am not satisfied that any of these arguments are absolutely conclusive. I will try to state briefly and clearly what seem to me the main arguments against the view that these are merely psychological ideas; although, in doing so, I am faced with a certain difficulty. For though, as I have said, many philosophers are absolutely convinced, that "duty" and "good" do merely stand for psychological ideas, they are by no means agreed _what_ the psychological ideas are for which they stand. Different philosophers have hit on very different ideas as being the ideas for which they stand; and this very fact that, if they _are_ psychological ideas at all, it is so difficult to agree as to _what_ ideas they are, seems to me in itself to be an argument against the view that they are so. Let me take each of the two ideas separately, and try to exhibit the sort of objection there seems to be to the view that it is merely a psychological idea. Take first the idea of moral obligation. What purely psychological assertion can I be making about an action, when I assert that it was "wrong," that it ought not to have been done?