Wittgenstein on the Inverted Spectrum

Abstract

The Stanford Encyclopedia of Philosophy entry on Inverted begins by noting Qualia inversion thought experiments are ubiquitous in contemporary philosophy of mind (largely due to the influence of Shoemaker 1982 and Block 1990). The most popular kind is or another variant of Locke's hypothetical case of “spectrum inversion”, in which strawberries and ripe tomatoes produce visual experiences of the sort are actually produced by grass and cucumbers, grass and cucumbers produce experiences of the sort are actually produced by strawberries and ripe tomatoes, and so on. This paper reviews and evaluates what Wittgenstein had to say on the topic. In the Philosophical Investigations , Wittgenstein observes the idea of private experience, that nobody knows whether other people also have this or something else (sec 272) supports the assumption it is possible, but unverifiable, one part of mankind had sensation of red, and part another, and thus the possibility of spectrum inversion. However, he does not explicitly discuss such hypotheses. Recently, Block (2007) has drawn attention to Wittgenstein's discussion of spectrum inversion in the Notes for Lectures on 'Sense Data.' There, Wittgenstein discusses cases in which we should say the person sees green what I see red (Wittgenstein 1993, 285), conceding a single person case of spectrum inversion is conceivable, but denying this could always be the case. Block argues a slippery slope leads from the concession of the possibility of spectrum inversion in a particular case to a scenario in which many people experience long-term spectrum inversion, and such scenarios are verifiable hypotheses. I evaluate Block's critique of Wittgenstein, and Canfield's (2009) response to Block's reading.