  One might think that at least step 4 is unproblematic. However, according to the “Frege-Schlick view” (Shoemaker 1982, 339), interpersonal comparisons of qualia (unlike intrapersonal comparisons) do not make sense. The Frege-Schlick view could be supported on verificationist grounds; for a more interesting line of defense, see Stalnaker 1999, 2006, and Shoemaker 2006b and Block 2007, 103–7, for discussion. Since it makes perfect sense (and indeed is often true) to say that tomatoes look red to most people, a proponent of the Frege-Schlick view must deny, for example, that \(Q_{R}\) is the property of being an experience of something’s looking red (see section 1 above and Stalnaker 1999, 225).