It may be true that all things which are good are also something else, just as it is true that all things which are yellow produce a certain kind of vibration in the light. And it is a fact, that Ethics aims at discovering what are those other properties belonging to all things which are good. But far too many philosophers have thought that when they named those other properties they were actually defining good; that these properties, in fact, were simply not "other," but absolutely and entirely the same with goodness. [Principia Ethica, 10:3]As for the second part of his argument, Moore acknowledges that others see him as a ‘moral intuitionist’, but insists that there are two layers to his ethical investigation, and that only the first of these—what is ‘good’?—is properly intuitive; the second layer, broadly ‘how should we act?’ is not, at least according to his argument. This from the preface to the Principia Ethica:
In order to express the fact that ethical propositions of my first class are incapable of proof or disproof, I have sometimes followed Sidgwick's usage in calling them ‘Intuitions.’ But I beg that it may be noticed that I am not an ‘Intuitionist,’ in the ordinary sense of the term. Sidgwick himself seems never to have been clearly aware of the immense importance of the difference which distinguishes his Intuitionism from the common doctrine, which has generally been called by that name. The Intuitionist proper is distinguished by maintaining that propositions of my second class—propositions which assert that a certain action is right or a duty—are incapable of proof or disproof by any enquiry into the results of such actions. I, on the contrary, am no less anxious to maintain that propositions of this kind are not ‘Intuitions,’ than to maintain that propositions of my first class are Intuitions.J L Mackie, Ethics: Inventing Right and Wrong (1977) thinks belief in ‘objective rights and wrongs’ cannot be sustained. He is not oblique about this: his book opens with the sentence ‘There are no objective values’, and its burden is that ethics must be invented rather than discovered.
If there were objective values, then they would be entities or qualities or relations of a very strange sort, utterly different from anything else in the universe. Correspondingly, if we were aware of them, it would have to be by some special faculty of moral perception or intuition, utterly different from our ordinary ways of knowing everything else. These were recognized by Moore when he spoke of non-natural qualities, and by the intuitionists in their talk about a ‘faculty of moral intuition’.Thomas Nagel (The View from Nowhere, ch. VIII) is not impressed by this argument. Mackie
denies the objectivity of values by saying they are “not part of the fabric of the world”, and that if they were they would have to be “entities or qualities or relations of a very strange sort, utterly different from anything else in the universe”. He clearly has a definite picture of what the universe is like, and assumes hat realism about values would require crowding it with extra entities or qualities or relations, things like Platonic Forms or Moore’s non-natural qualities. But this assumption is not correct. The objective badness of pain, for example, is not some mysterious further property that all pains have, but just the fact that there is reason for anyone capable of viewing the world objectively to want it to stop. The view that values are real is not the view that they are real occult entities or properties, but that they are real values: that our claims about value and about what people have reason to do may be true or false independent of our beliefs and inclinations.Pain, broadly, is bad—unless, we might say, one is a masochist; but then again, leprosy is bad too, so I wonder if Nagel’s ‘anyone capable of viewing the world objectively’ can do the work his thought requires of it. Real values are surely infintely negotiable?
Incidentally, I found this excellent account of the valences of Nagel's title, though I've forgotten where:
The puzzle is this: we see the world from a point of view, namely, the point of view of our own conscious selves. As babies, we only have a view of the world from this viewpoint. But as we grow older, we also have what Nagel calls the "view from nowhere". This is the idea of the world as objectively existing, independently of both our viewpoint or any other particular viewpoint. We consider ourselves to be a part of this world. Therefore we have a view of ourselves from the inside as perceivers of the world, but also of ourselves as members of the objective world.
Common-sense tells us that when we accumulate knowledge, this knowledge includes knowledge of the objective world. But Nagel sees a problem in the enterprise of accumulating such knowledge. Objective knowledge requires a neutral perspective. But we cannot occupy this neutral perspective. Therefore, objective knowledge seems unattainable.
What we try to do is give an account of the world that "includes an explanation of why it initially appears to us as it does". The problem here is that, while doing this, we always have to keep our subjective perspective, so there is always room for doubt that we are not getting the proper picture. "The most objective view we can achieve will have to rest on an unexamined subjective base."
The skeptical response to this is to accept that we just can’t have knowledge of the objective world. For all we know, we might live in the Matrix.
However, skepticism isn’t the only response to this. One alternative is a reductive response, which is anti-skeptical in nature. Nagel writes, "On a reductive view our beliefs are not about the world as it is in itself ... they are about the world as it appears to us." As what we commonly understand by objective knowledge is not possible, it is accepted that reality beyond our experience is either not possible or meaningless and so knowledge is understood as being confined to what is possible for us to experience.
The third possible response is the heroic one. This attempts somehow to bridge the gap between ourselves and objective knowledge. Part of the reason for calling this heroic is that the odds seemed stacked against its success.
Nagel also makes a distinction between realist and non-realist positions. The skeptical and heroic views are realist because both hold that there is a really existent outside world which we either can (heroic) or cannot (skeptical) comprehend. The reductive view on the other hand, sees this all as a red herring. It can only make sense to talk of how we see the world. The idea of an objectively existing world just doesn’t make any sense. However, Nagel believes that only realist response to the problem are credible, and wants to pursue a heroic one.