Instrumental Rationality

Instrumental rationality is the capacity to choose effective means for achieving given ends. It is the most formalized and least controversial conception of rationality: an agent is instrumentally rational if their actions are well-calibrated to their goals, given their beliefs about how the world works. Game theory and decision theory are largely theories of instrumental rationality, specifying how agents should select strategies when outcomes depend on their choices.

The limits of instrumental rationality are precisely its formal power. It presupposes that ends are given and fixed, which they rarely are. It presupposes that beliefs are accurate, which they often are not. And it presupposes that the agent is acting alone, whereas most consequential choices are embedded in social systems where individual optimization produces collective failure. Instrumental rationality is necessary but not sufficient for rational agency in the full sense.