Hume, Reason and Morality: A Legacy of Contradiction

Routledge: London, February 2006



This book claims that there is a contradiction at the heart of one of the most potent arguments in moral philosophy. The argument is among a cluster used by Hume in Book 3 of the Treatise to demonstrate that “moral distinctions [are] not deriv'd from reason”. In this argument, he seeks to derive the conclusion from morality's practicality. The contradiction occurs in the second premiss - formulated no less than nine times - and concerns whether reason can, or cannot, influence action. Not only has this contradiction been almost universally ignored, but it has even been reproduced, without comment, in recent meta-ethical debate as a kind of orthodoxy. My clarification of the confusions thus engendered will lead to the undermining of the traditional opposition between cognitivism, claiming that moral judgements are beliefs, and non-cognitivism that they are desires, as these theories bear on moral motivation. It will also bring to light the source of the argument's power in an article of naturalistic dogma. This will finally suggest how, using Wittgensteinian ideas to resist the simple dichotomy either naturalism or metaphysical obscurantism, it may be possible to restore to moral concepts their traditional and integral link with both truth and motivation.

The main device that I use in the book for exploring the contradiction, and its consequences, is to treat the ‘practicality' argument as if there were compressed within its apparently unitary structure two arguments, depending on which of the contradictory readings of the second premiss is given. I call the argument with a second premiss claiming that reason can, and does, influence action, though only alongside desire, the ‘moderate' version. The argument whose second premiss denies that reason has, or could have, any motivating role is the ‘extreme' version. This strategy bears fruit not only in the discussion of Hume, but also when applied to the contemporary scene. For what initially seemed like a jumble of interpretations are plausibly sorted into ‘moderate' and ‘extreme' versions of the argument.

The chief drawback with the ‘moderate' version is that, as it stands, it is invalid. Indeed many recent reinterpretations of the argument are best seen as attempts to redress this invalidity by philosophers who have automatically, and without being fully aware of it, assumed this version. Their solution is often simply to read back into Hume's first premiss a necessary, or “internal”, link between moral judgements and motivation, though in fact the relation that Hume claims to hold is much looser.

The ‘extreme' version, though being immediately valid, suffers from another problem. This is the apparent obscurity, if not absurdity, of the claim - to cite one of Hume's more spectacular statements of the second premiss - that “reason is perfectly inert”. But if it is difficult to see what Hume himself might have meant by this declaration, or who therefore could have been his target, the problem is intensified when it is appealed to by a recent philosopher such as Bernard Williams (1981). In trying to solve the puzzle of the identity of Williams' opponents here, I gradually lay bare the deeper structure of assumptions which has invisibly shaped, and even sometimes dictated the form of contemporary meta-ethical debate.

As far as the source of the contradiction itself is concerned it lies, I argue, in a scepticism - I call it an unappeasable scepticism - which Hume, towards the end of Book 1, both passionately endorses and violently repudiates. He does this by using the device of the ‘philosopher secluded in his closet' and the ‘honest gentleman' in the midst of his domestic affairs. Through this almost theatrical contrast Hume is able to rebel against the idea that our beliefs might ultimately be without foundation at the very same time as he is ruthlessly pushing the limits of his scepticism ever further out, beyond belief, to undermine demonstrative reasoning itself.

A final word on my method. My chapters on Hume's Treatise are not a measured progression through the text following the order in which Hume treats his topics. I am rather engaged on a journey of discovery which takes us sometimes forward, sometimes backward. I thus plunge, as it were, cold, into Book 3 where our problem initially lies, and then I find myself pushed backward, through Book 2, to Book 1 because I am not able to resolve it any other way. This method suits a writer such as Hume much better than the more ‘linear' alternative that is usually followed. For in those extraordinary sections towards the end of Book 1 where Hume confronts his scepticism head-on, and his viewpoint then oscillates back and forth between the ‘philosopher in his closet' and ‘the honest gentleman', engaged in back-gammon and other such pursuits, we glimpse Hume's different ‘voices', providing a counter-point of incomparable richness, so grievously lost in that tame set of views known officially as “Humeanism”. To explain away Hume's inconsistencies is not the best way of rendering service to a philosopher, part of whose greatness lies in the very contradictions on which his multi-faceted genius thrives.