"A misleading though attractive distinction is made by many thinkers between fact and (moral) value. Roughly, the purpose of the distinction ... is to segregate value in order to keep it pure and untainted, not derived from or mixed with empirical facts. This move however, in time and as interpreted, may in effect result in a diminished, even perfunctory, account of morality, leading (with the increasing prestige of science) to a marginalisation of 'the ethical'. ... This originally well-intentioned segregation then ignores an obvious and important aspect of human existence, the way in which almost all our concepts and activities involve evaluation. ... [I]n the majority of cases, a survey of the facts will itself involve moral discrimination. ... Much of our life is taken up by truth-seeking, imagining, questioning. We relate to facts through truth and truthfulness, and come to recognise and discover that there are different modes and levels of insight and understanding. In many familiar ways various values pervade and colour what we take to be the reality of our world; wherein we constantly evaluate our own values and those of others, and judge and determine forms of consciousness and modes of being. To say all this is not in any way to deny either science, empiricism or common-sense. ... A proper separation of fact and value, as a defence of morality, lies in the contention that moral value cannot be derived from fact."
--Iris Murdoch, Metaphysics as a Guide to Morals (1992)