A view is presented according to which scientific change, including radical change in the most fundamental scientific conceptions, takes place for reasons. In addition to changes in meanings and substantive claims, such change also often involves alterations in standards, goals, and methods of science. Some of the strengths of this view, as contrasted with some major alternative interpretations of science, are sketched. In particular, the view that some ideas, in some theories or traditions, are "incommensurable" with ideas in at least some other scientific theories or traditions is analyzed critically and reinterpreted.