J. L. Mackie

[I]t is quite true that it is logically possible that the subjective concern, the activity of valuing or of thinking things wrong, should go on in just the same way whether there are objective values or not. But to say this is only to reiterate that there is a logical distinction between first and second order ethics: first order judgments are not necessarily affected by the truth or falsity of a second order view. But it does not follow, and it is not true, that there is no difference whatever between these two worlds. In the one there is something that backs up and validates some of the subjective concern which people have for things, in the other there is not. Hare’s argument is similar to the positivist claim that there is no difference between a phenomenalist or Berkeleian world in which there are only minds and their ideas and the commonsense realist one in which there are also material things, because it is logically possible that people should have the same experiences in both. If we reject the positivism that would make the dispute between realists and phenomenalists a pseudo-question, we can reject Hare’s similarly supported dismissal of the issue of the objectivity of values.

J. L. Mackie, Ethics: Inventing Right and Wrong, London, 1977, pp. 19-20