  David Lewis has mounted a challenge to such theories of desire on the basis of results from decision theory (Lewis 1988; 1996). Lewis considers the thesis, Desire As Belief, that a rational individual is motivated to make true a proposition p to the extent that she believes p to be good, and shows that within a familiar decision-theoretic framework inconsistencies result. In Lewis's argument, the result follows because of the differences between rational belief revision and rational desire (or motivation) revision within the decision-theoretic framework. In response to Lewis, a number of philosophers have sought to defend the general idea that desires are beliefs in goodness (or are entailed by such beliefs in rational individuals) by defending different specific formulations of the thesis within decision theory (e.g., Price 1989; Byrne and Hájek 1997). There have also been efforts to show that formal decision theory might not be formalizing the right things to draw conclusions about desire and goodness (e.g., Broome 1991).