practical reason the capacity for argument or demonstrative inference, considered in its application to the task of prescribing or selecting behavior. Some philosophical concerns in this area pertain to the actual thought processes by which plans of action are formulated and carried out in practical situations. A second major issue is what role, if any, practical reason plays in determining norms of conduct. Here there are two fundamental positions.
Instrumentalism is typified by Hume’s claim that reason is, and ought only to be, the slave of the passions. According to instrumentalism, reason by itself is incapable of influencing action directly. It may do so indirectly, by disclosing facts that arouse motivational impulses. And it fulfills an indispensable function in discerning means–end relations by which our objectives may be attained. But none of those objectives is set by reason. All are set by the passions – the desiderative and aversive impulses aroused in us by what our cognitive faculties apprehend. It does not follow from this alone that ethical motivation reduces to mere desire and aversion, based on the pleasure and pain different courses of action might afford. There might yet be a specifically ethical passion, or it might be that independently based moral injunctions have in themselves a special capacity to provoke ordinary desire and aversion. Nevertheless, instrumentalism is often associated with the view that pleasure and pain, happiness and unhappiness, are the sole objects of value and disvalue, and hence the only possible motivators of conduct. Hence, it is claimed, moral injunctions must be grounded in these motives, and practical reason is of interest only as subordinated to inclination.
The alternative to instrumentalism is the view championed by Kant, that practical reason is an autonomous source of normative principles, capable of motivating behavior independently of ordinary desire and aversion. On this view it is the passions that lack intrinsic moral import, and the function of practical reason is to limit their motivational role by formulating normative principles binding for all rational agents and founded in the operation of practical reason itself. Theories of this kind usually view moral principles as grounded in consistency, and an impartial respect for the autonomy of all rational agents. To be morally acceptable, principles of conduct must be universalizable, so that all rational agents could behave in the same way without their conduct either destroying itself or being inconsistently motivated. There are advantages and disadvantages to each of these views. Instrumentalism offers a simpler account of both the function of practical reason and the sources of human motivation. But it introduces a strong subjective element by giving primacy to desire, thereby posing a problem of how moral principles can be universally binding. The Kantian approach offers more promise here, since it makes universalizability essential to any type of behavior being moral. But it is more complex, and the claim that the deliverances of practical reason carry intrinsic motivational force is open to challenge. See also INSTRUMENTALISM, KANT, MOTI- VATIONAL INTERNALISM , PRACTICAL REA – SONING , RATIONALIT. H.J.M.