Donald Davidson's work on the nature of the mind has had a major impact on contemporary discussions in philosophy of mind; it is fair to say that no other philosopher has been more influential in shaping the basic contours of the field as it exists today. As is true in the case of many other philosophers, both of his generation and of following generations, his reflections on mind and its relation to matter have been carried on with a set of broad physicalist assumptions as a backdrop. Precisely what these assumptions are is not easy to say, and it is not necessary to set them down in exact formulations. For most philosophers who have reflected on the status of mind, including Davidson, the main task has been that of finding for mind a place in an essentially physical world. The world is fundamentally a physical world in that the space-time world is the entire world, and that within space-time we find nothing but bits of matter and increasingly complex aggregates made up of bits of matter. As C. Lloyd Morgan, one of the early emergentists, aptly put it, there is “no insertion of alien forces” (Morgan 1923) when complex physical systems are generated out of simpler ones; there are only material elements arranged in new relationships and structures. These material entities have various physical properties – mass, motion, energy, electric charge, temperature, elasticity, and the like – and they behave in accordance with the laws of physics.