Recent attempts by sociobiologists to provide an evolutionary basis for ethics have generally failed to persuade philosophers that the old objections to such theories can be overcome. These objections have been variously formulated, but they all amount to the accusation that any attempt to derive morally significant principles or judgments from our evolutionary history must commit the naturalistic fallacy. In its most common formulation the doctrine of the naturalistic fallacy claims that it is not possible validly to derive an ethical conclusion from a set of premises which are entirely factual. Such attempts to derive values from facts, it is claimed, all commit a logical fallacy, which Moore termed 'the naturalistic fallacy.' The recent forays by sociobiologists into ethics have all seemed blatantly to commit the naturalistic fallacy, and it is therefore not surprising that philosophers have been unimpressed.
On the other hand, it is not surprising that sociobiologists have been unimpressed by the doctrine of the the naturalistic fallacy, for its implications seem to be absurd. If values cannot be grounded on facts, then presumably they can only be grounded on other values. But these other values can themselves only be grounded on even more fundamental values, and if we are to avoid an infinite regress we end with some fundamental values that cannot be grounded at all. This, however, means that the whole structure of values is essentially groundless. Values thus come to be seen as either unreal, or completely arbitrary. If they are unreal then the only rational position is to seek to eradicate moral and ethical language altogether, and replace it with the language of needs or wants. If they are arbitrary then anything goes, for there is literally nothing that can be said to justify or to refute any value judgment whatsoever. In either case, ethics as a subject for serious study no longer exists.
Most philosophers have not been willing to accept these conclusions and have used a variety of strategies to defuse the sting of the naturalistic fallacy. G. E. Moore (1903) held that ethics could be grounded in an intellectual intuition of the nature of the good, although most philosophers have refused to follow him in this. The most common strategy is to give up the search for proofs in ethics and to employ a weaker criterion of reasonableness. Some (e.g. Hare 1963) have held that there are a few general