Recently, researchers have begun to empirically investigate the gender gap in philosophy and provide potential explanations for the underrepresentation of women in philosophy relative to their representation in other disciplines. This empirical research as well as research on the gender gap in Science, Technology, Engineering, and Mathematics fields has shed light on a priori, armchair explanations of the gender gap. For example, implicit bias and stereotype threat may contribute much less to the philosophy gender gap than previously thought. However, new candidate contributing factors have emerged. Drawing on the theoretical resources concerning fixed mindsets in response to difficult tasks, a new theory suggests that practitioners in various fields, including philosophy, hold the belief that success in their fields requires natural brilliance (a brilliance-based field-specific ability belief). Further, the extent to which members of a field hold that belief predicts the diversity of the members of that field. Initial findings suggest that among the set of students who hold these beliefs, women are disproportionately disinterested in continuing in philosophy. Other hypotheses seem plausible, such as the idea that lay people hold gendered schemas about philosophy, but require more empirical support to be partial explanations. Future empirical research should focus on these plausible hypotheses, replications of previous findings, and investigating the effects of intersectionality within the gender gap.