James Owen Weatherall (California) gives a talk at the MCMP Colloquium (19 July, 2013) titled "Inertial Motion, Explanation, and the Foundations of Classical Spacetime Theories". Abstract: There is an influential view in physics and philosophy of physics, originating with Einstein and Eddington, that holds that general relativity is distinctive in the history of physics because it can be used to "explain" inertial, or unforced, motion. In this talk, I will describe how a reformulation of Newtonian gravitation may be used to provide insight into claims concerning the (allegedly) distinctive explanatory resources of relativity theory. I will then argue that Newtonian gravitation can be understood to explain inertial motion in much the same way as general relativity. However, a careful comparative study of the status of inertial motion in the two theories reveals that neither explanation is as clean or straightforward as adherents to the view noted above believe. I will conclude by presenting a view about the interdependencies of the central principles of physical theories that I will argue provides some insight into a sense in which inertial motion is explained in both of these theories.