  Some philosophers hold that indexical attitudes, and so indexicals themselves, are important to understanding philosophically significant phenomena such as the following: Agency and explanation of action (Castañeda 1975; Perry 1979, 2000; McGinn 1983; and the entry on   action); self-consciousness, subjectivity, and the first-person perspective (Nagel 1986, McDowell 1998); consciousness and qualia (Perry 1999;  and the entries on    consciousness and    qualia); perceptual content (Egan 2006;  and the entry on    the contents of perception);  immunity to error through misidentification (Shoemaker 1968); secondary qualities (McGinn 1983; Egan 2006); and various issues in moral philosophy (Velleman 1999; Hare 2007). For skepticism about the importance of indexicals to one or more of these topics, see Millikan 1990, Cappelen and Dever 2013, and Magidor forthcoming.