MacIntyre on the Enlightenment project’s logical incoherence

“The moral scheme which forms the historical background to their thought had, as we have seen, a structure which required three elements:
untutored human nature, man-as-he-could-be-if-he-realized-his-telos and the moral precepts which enable him to pass from one state to the other. But the joint effect of the secular rejection of both Protestant and Catholic theology and the scientific and philosophical rejection of Aristotelianism was to eliminate any notion of man-as-he-could-be-if-he-realized-his-telos. Since the whole point of ethics-both as a theoretical and a practical discipline – is to enable man to pass from his present state to his true end, the elimination of any notion of essential human nature and with it the abandonment of any notion of a telos leaves behind a moral scheme composed of two remaining elements whose relationship becomes quite unclear. There is on the one hand a certain content for morality: a set of injunctions deprived of their teleological context. There is on the other hand a certain view of untutored-human-nature-as-it-is. Since the moral injunctions were originally at home in a scheme in which their purpose was to correct, improve and educate that human nature, they are clearly not going to be such as could be deduced from true statements about human nature or justified in some other way by appealing to its characteristics. The injunctions of morality, thus understood, are likely to be ones that human nature, thus understood, has strong tendencies to disobey. Hence the eighteenth-century moral philosophers engaged in what was an inevitably unsuccessful project; for they did indeed attempt to find a rational basis for their moral beliefs in a particular understanding of human nature, while inheriting a set of moral injunctions on the one hand and a conception of human nature on the other which had been expressly designed to be discrepant with each other. This discrepancy was not removed by their revised beliefs about human nature. They inherited incoherent fragments of a once coherent scheme of thought and action and, since they did not recognize their own peculiar historical and cultural situation, they could not recognize the impossible and quixotic character of their self-appointed task.


This change of character, resulting from the disappearance of any connection between the precepts of morality and the facts of human nature already appears in the writings of the eighteenth-century moral philosophers themselves. For although each of the writers we have been concerned with attempted in his positive arguments to base morality on human nature, each in his negative arguments moved toward a more and more unrestricted version of the claim that no valid argument can move from entirely factual premises to any moral or evaluative conclusion-to a principle, that is, which once it is accepted, constitutes an epitaph to their entire project. Hume still expresses this claim in the form of a doubt rather than of a positive assertion. He remarks that in ‘every system of morality, which I have hitherto met with’ authors make a transition from statements about God or human nature to moral judgments: ‘instead of the usual copulations of propositions, is, and is not, I met with no proposition that is not connected with an ought, or an ought not’ (Treatise Ill. i. 1). And he then goes on to demand ‘that a reason should be given, for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it’


From such factual premises as ‘This watch is grossly inaccurate and irregular in time-keeping’ and ‘This watch is too heavy to carry about comfortably’, the evaluative conclusion validly follows that ‘This is a bad watch’. From such factual premises as ‘He gets a better yield for this crop per acre than any farmer in the district’, ‘He has the most effective programme of soil renewal yet known’ and ‘His dairy herd wins all the first prizes at the agricultural shows’, the evaluative conclusion validly follows that ‘He is a good farmer’.
Both of these arguments are valid because of the special character of the concepts of a watch and of a farmer. Such concepts are functional concepts; that is to say, we define both ‘watch’ and ‘farmer’ in terms of the purpose or function which a watch or a farmer are characteristically expected to serve. It follows that the concept of a watch cannot be defined independently of the concept of a good watch nor the concept of a farmer independently of that of a good farmer; and that the criterion of something’s being a watch and the criterion of something’s being a good watch-and so also for ‘farmer’ and for all other functional concepts-are not independent of each other. Now clearly both sets of criteria-as is evidenced by the examples given in the last paragraph-are factual. Hence any argument which moves from premises which assert that the appropriate criteria are satisfied to a conclusion which asserts that ‘That is a good such-and-such’, where ‘such-and-such’ picks out an item specified by a functional concept, will be a valid argument which moves from factual premises to an evaluative conclusion. Thus we may safely assert that, if some amended version of the ‘No ~ought” conclusion from “is” premises’ principle is to hold good, it must exclude arguments involving functional concepts from its scope. But this suggests strongly that those who have insisted that all moral arguments fall within the scope of such a principle may have been doing so, because they took it for granted that no moral arguments involve functional concepts. Yet moral arguments within the classical, Aristotelian tradition-whether in its Greek or its medieval versions – involve at least one central functional concept, the concept of man understood as having an essential nature and an essential purpose or function; and it is when and only when the classical tradition in its integrity has been substantially rejected that moral arguments change their character so that they fall within the scope of some version of the ‘No “ought” conclusion from “is” premises’ principle. That is to say, ‘man’ stands to ‘good man’ as ‘watch’ stands to ‘good watch’ or ‘farmer’ to ‘good farmer’ within the classical tradition. Aristotle takes it as a standing-point for ethical enquiry that the relationship of ‘man’ to ‘living well’ is analogous to that of ‘harpist’ to ‘playing the harp well’ (Nicomacbean Ethics, 1095a 16). But the use of ‘man’ as a functional concept is far older than Aristotle and it does not initially derive from Aristotle’s metaphysical biology. It is rooted in the forms of social life to which the theorists of the classical tradition give expression. For according to that tradition to be a man is to fill a set of roles each of which has its own point and purpose: member of a family , citizen, soldier, philosopher, servant of God. It is only when man is thought of as an individual prior to and apart from all roles that ‘man’ ceases to be a functional concept.”

p54-59 After Virtue

No telos means you are left with deontology, consequentialism, utilitarianism etc.