Mary specializes in ethics and philosophy of action. She is also interested in metaphysics, philosophy of mind, and the history of early modern philosophy. In her current research, Mary is investigating the relationship between the nature of action and the foundations of ethics. For example, she is arguing for the surprising, controversial idea that significant truths about which actions we ought to perform follow from the nature of action itself.

Mary has been awarded a Faculty Fellowship from the Murphy Institute's Center for Ethics and Public Affairs at Tulane University for the 2012-13 academic year.