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Show Rationality and the Structure of the Self, Volume I: The Humean Conception 261 Thomas Nagel's The Possibility of Altruism1 is the first and only post-war attempt in the Anglo-American tradition to furnish an extended, genuinely non-Humean internalist account of moral motivation. Several decades after its publication, it remains the unsurpassed modern classic of Kantian rationalist moral psychology. However, it does not carve out a clear and identifiable alternative to the belief-desire model of motivation, nor does it mean to. Nagel's stated project is to articulate the rational ethical criteria by which the rationality of desire can be evaluated. What he actually does is to attack the premise that desire of any kind must motivate action - without, however, explicating a clear alternative to replace it. But Kantians such as Nagel who in effect accept the Humean model are hard pressed to explain how we can be morally motivated at all in its absence. Without such an alternative, it is unclear how the rational ethical criteria for evaluating desire Nagel develops might, as a precipitating cause of action, occurrently influence the desires we happen to have. In this case externalism looms, and the Humean is free to reassert the primacy of desire as the only plausible candidate for human motivation. Because Nagel rejects the hypothesis that only occurrent desire-states are motivationally effective in causing action, but declines to supply an alternative account of how actions may be caused, he has only one choice: to modify the belief-desire model so as to accommodate the motivational efficacy of reason within it. Nagel distinguishes between "unmotivated" desires that just assail us, such as appetites, and "motivated" desires that may be caused by prior desires, reasoning, or deliberation. He then argues that motivated desires are desires only in the vacuous sense, since whatever explains them also explains the actions they purportedly cause. Among the factors that may explain them, he claims, are certain impartial rational principles expressive of one's self-conception as one temporally extended agent among many, i.e. principles of prudence and altruism. However, Nagel does not explain how a self-conception, or the principles that express it, can occurrently cause one to do something. In the absence of some such recognizably causal factor, the Humean is free to retort that since we are not rationally required to accept this self-conception, the principles that express it can be motivationally effective only if one desires in the unmotivated sense to accept it. Then not only have these rational principles not been shown to be motivationally effective independent of desire; they have not been given a nonarbitrary rational justification, either. Nagel's project does contain the resources for an identifiable alternative to the Humean model, however: What Nagel could and should have said was that the description of a motivated desire may denote a particular episode of reasoning as a motivationally (Oxford: Clarendon Press, 1975). Henceforth all page references to this work will be parenthecized in the text. 1 © Adrian Piper Research Archive Foundation Berlin |
