Version: v2, Published online: 2005
Retrieved January 23, 2019, from https://www.rep.routledge.com/articles/biographical/hume-david-1711-76/v-2
Philosophers from PLATO to Spinoza have recommended actions motivated by reason rather than passion. Hume argues, however, that just as reason cannot produce the key transition in probable inference or the belief in an external world of bodies, so too reason alone cannot determine the will to act. His primary argument (THN 2.3.3) is as follows. All reasoning is either demonstrative or probable. Because demonstrative reasoning discovers only relations of ideas – primarily mathematical relations – and does not discover the actual existence or non-existence of things, it cannot motivate any action directly, but affects action only by facilitating the mathematical formulation and application of causal generalizations. Probable reasoning, which discovers causal relations themselves through experience, can serve to direct action by showing the means to a desired end, but cannot alone motivate it. For as long as objects do not affect one’s passions (including desire and aversion), the will remains indifferent to their causal relations. Furthermore, since reason could oppose an operation of the will only by providing a contrary motivation, reason can never oppose passion in the direction of the will. Hence, Hume declares, ‘reason is, and ought only to be, the slave of the passions, and can never pretend to any other office than to serve and obey them’.
In further support of this conclusion, Hume argues that passions are ‘original existences’ lacking any representative quality, and hence cannot be opposed to the claims to truth produced by reasoning. Reason can never oppose a passion, but only a judgment accompanying a passion. Where a passion concerns an object judged to exist but which does not really exist, or where action takes particular form due to a false belief that something stands as a causal means to a desired end, the passion itself may be called ‘unreasonable’, but only in an improper sense, for it is the accompanying judgment that is unreasonable. The appearance that reason and passion can struggle for the determination of the will results largely from the existence of ‘calm passions’ – such as the general appetite to pleasure and aversion to evil as such – that feel, in their operation, much like the calm operations of reason.
Hume is sometimes characterized as holding a limited conception of ‘practical reason’: namely, that passions determine one’s ends, and that the only form of practical reasoning is the generation of new desires or actions from given ends and beliefs about the means to those ends. On this view, then, one acts irrationally only when one fails to pursue the means to one’s ends. In fact, however, Hume rejects even this limited conception. For him, the outcome of reasoning itself is belief, not desire or action; and although reasoning can, in concert with other aspects of one’s nature, contribute to the production of new desires and actions, this process of production is not itself one of reasoning. While Hume regards failing to take the acknowledged means to one’s ends as folly and subject to criticism, therefore, it is only in an improper sense ‘irrational’.
Garrett, Don. Motivation. Hume, David (1711–76), 2005, doi:10.4324/9780415249126-DB040-2. Routledge Encyclopedia of Philosophy, Taylor and Francis, https://www.rep.routledge.com/articles/biographical/hume-david-1711-76/v-2/sections/motivation.
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