In standard decision theory, rational agents are objective, keeping their beliefs independent from their desires. Such agents are the basis for current computational models of Theory of Mind (ToM), but this fundamental assumption of the theory remains untested. Do people think that others' beliefs are objective, or do they think that others' desires color their beliefs? We describe a Bayesian framework for exploring this relationship and its implications. Motivated by this analysis, we conducted two experiments testing the a priori independence of beliefs and desires in people's ToM and find that, contrary to fully-normative accounts, people think that others engage in wishful thinking. People's ToM therefore appears to be more nuanced than the current rational accounts, but consistent with a model in which desire directly affects the subjective probability of an event.