"Distinguishable, not separable." I'll accept that, but Mars remains red in the sense that human eyes perceive the light coming from that object in a certain way & humans have a name for that sensation; if the name for the color were blue, the situation wouldn't really be any different, only the label would have changed, not the underlying reality. (Christ! I know that is a term fraught with problems, but, in the Wittgensteinian sense, you know what I mean!) I accept Wittgenstein's critique of the Positivist word/object relation. Dogs, however, bereft of language, can identify colors & certainly can form opinions about objects. What if we say that human beings organize their perceptions of the world in language? Such a statement avoids the vortex of idealism without insisting that we know exactly what produces our perceptions--of color or anything else.
Christopher Robinson & Joseph Duemer read Wittgenstein's Philosophical Investigations