 Furthermore, Feyerabend’s concept of incommensurability of scientific theories was much more restricted than Kuhn’s. For Kuhn, incommensurability had three prima facie heterogeneous domains, holistically bound: a change of problems and standards, a change of concepts used to state and solve them, and a change of world-view in which they arise. Feyerabend’s focus, on the other hand, was initially exclusively on concepts occurring in universal or fundamental theories, together with their ontological implications. Ironically, however, in developments after 1962, both authors move in opposite directions. Kuhn gradually eliminated everything from his notion of incommensurability that does not concern scientific concepts, and ended more or less where Feyerabend began (see Carrier 2001; Chen 1997; Hoyningen-Huene 1990, 487-488; Hoyningen-Huene 1993, 212-218; Hoyningen-Huene 2004, Sankey 1993; Sankey 1994, 16-30; Sankey 1997). Feyerabend, by contrast, increasingly emphasized aspects of perceptual change (1975, 225–229, 273–274; 1978, 68; 1988, 172–176), and also changes to the set of legitimate problems a discipline should handle (1975, 274–275), and his later philosophy emphasizes one of Kuhn’s original points; the role of non-binding, epistemic values in theory choice (cf. Farrell 2003).