Many philosophers hold that for various reasons there must be psychological laws governing beliefs and desires. One of the few serious examples that they offer is the _belief-desire law_, which states, roughly, that _ceteris paribus_ people do what they believe will satisfy their desires. This paper argues that, in fact, there is no such law. In particular, decision theory does not support the contention that there is such a law.

Individual differences on a variety of framing and conjunction problems were examined in light of Slovic and Tversky's (1974) understanding/acceptance principle-that more reflective and skilled reasoners are more likely to affirm the axioms that define normative reasoning and to endorse the task construals of informed experts. The predictions derived from the principle were confirmed for the much discussed framing effect in the Disease Problem and for the conjunction fallacy on the Linda Problem. Subjects of higher cognitive ability were disproportionately likely (...) to avoid each fallacy. Other framing problems produced much more modest levels of empirical support. It is conjectured that the varying patterns of individual differences are best explained by two-process theories of reasoning (e.g. Evans, 1984, 1996; Sloman, 1996) conjoined with the assumption that the two processes differentially reflect interactional and analytic intelligence. (shrink)

It is a mistake to think that instrumental rationality fixes a single standard for judging or describing actions. While there is a core conception of instrumental rationality, we appeal to different elaborations of that conception for different purposes. An action can be instrumentally rational in some sense(s) but not in others. As we learn more about behavior, it is possible to add useful elaborations of the core conception of instrumental rationality. In this paper, I propose a new elaboration based on (...) Frederic Schick's work on understandings. (shrink)

It is a mistake to think that instrumental rationality fixes a single standard for judging or describing actions. While there is a core conception of instrumental rationality, we appeal to different elaborations of that conception for different purposes. An action can be instrumentally rational in some sense(s) but not in others. As we learn more about behavior, it is possible to add useful elaborations of the core conception of instrumental rationality. In this paper, I propose a new elaboration based on (...) Frederic Schick's work on understandings. (shrink)