 Metaphysically, realism is committed to the mind-independent existence of the world investigated by the sciences. This idea is best clarified in contrast with positions that deny it. For instance, it is denied by any position that falls under the traditional heading of “idealism”, including some forms of phenomenology, according to which there is no world external to and thus independent of the mind. This sort of idealism, however, though historically important, is rarely encountered in contemporary philosophy of science. More common rejections of mind-independence stem from neo-Kantian views of the nature of scientific knowledge, which deny that the world of our experience is mind-independent, even if (in some cases) these positions accept that the world in itself does not depend on the existence of minds. The contention here is that the world investigated by the sciences—as distinct from “the world in itself” (assuming this to be a coherent distinction)—is in some sense dependent on the ideas one brings to scientific investigation, which may include, for example, theoretical assumptions and perceptual training; this proposal is detailed further in  section 4.  It is important to note in this connection that human convention in scientific taxonomy is compatible with mind-independence. For example, though Psillos (1999: xix) ties realism to a “mind-independent natural-kind structure” of the world, Chakravartty (2007a: ch. 6) argues that mind-independent properties are often conventionally grouped into kinds (see also Boyd 1999; Humphreys 2004: 22–25, 35–36, and cf. the “promiscuous realism” of Dupré 1993).