Unity of science

How should our scientific knowledge be organized? Is scientific knowledge unified and, if so, does it mirror a unity of the world as a whole? Or is it merely a matter of simplicity and economy of thought? Either way, what sort of unity is it? If the world can be decomposed into elementary constituents, must our knowledge be in some way reducible to, or even replaced by, the concepts and theories describing such constituents? Can economics be reduced to microphysics, as Einstein claimed? Can sociology be derived from molecular genetics? Might the sciences be unified in the sense of all following the same method, whether or not they are all ultimately reducible to physics? Considerations of the unity problem begin at least with Greek cosmology and the question of the one and the many. In the late twentieth century the increasing tendency is to argue for the disunity of science and to deny reducibility to physics.