Online research in philosophy

In this paper, I shall evaluate a strategy recently used to try to demonstrate the impossibility of behaviorally undetectable spectrum inversion. After showing that the impossibility proof proves too much, I shall identify where it goes wrong. In turn, I shall explain why someone attracted to functionalist and representationalist assumptions might rightly remain agnostic about the possibility of inversion.

Philosophers have adopted various names for the things in the beholder (or properties of the beholder) that have been supposed to provide a safe home for the colors and the rest of the properties that have been banished from the "external" world by the triumphs of physics: "raw feels", "sensa", "phenomenal qualities" "intrinsic properties of conscious experiences" "the qualitative content of mental states" and, of course, "qualia," the term I will use. There are subtle differences in how these terms have been defined, but I'm going to ride roughshod over them. I deny that there are.

A physicalist view of qualia labelled non-eliminative reductionism is outlined. If it is true, qualia and physicalism can co-exist without difficulty. First, qualia present no particular problem for reductionist physicalism - they are entirely physical, can be studied and explained using the standard scientific approach, and present no problem any harder than any other scientists face. Second, reductionist physicalism presents no particular problem for qualia – they can be encompassed within an entirely physicalist position without any necessity, either to reduce them to non-existence, or to treat them as new fundamental properties. It is suggested that the position also has sufficient explanatory power to successfully deal with the 'why like anything – why does experience exist at all' question and to counter both Chalmers' Conceivability Argument and Jackson's Knowledge Argument.

The possibility that what looks red to me may look green to you has traditionally been known as "spectrum inversion." This possibility is thought to create difficulties for any attempt to define mental states in terms of behavioral dispositions or functional roles. If spectrum inversion is possible, then it seems that two perceptual states may have identical functional antecedents and effects yet differ in their qualitative content. In that case the qualitative character of the states could not be functionally defined.

Formerly a spectral apparition that haunted behaviorism and provided a puzzle about our knowledge of other minds, the inverted spectrum possibility has emerged as an important challenge to functionalist accounts of qualia. The inverted spectrum hypothesis raises the possibility that two individuals might think and behave in the same way yet have different qualia. The traditional supposition is of an individual who has a subjective color spectrum that is inverted with regard to that had by other individuals. When he looks at red objects, this individual has the qualia normally produced in others by blue objects. And when presented with a blue object, this individual experiences qualia that most persons experience only when presented with red objects. And so forth - the Invert's color spectrum is the inverse of normal; there are systematic inter-subjective differences in qualia.

(Wittgenstein, 1968) endorsed one kind of inverted spectrum hypothesis and rejected another. This paper argues that the kind of inverted spectrum hypothesis that Wittgenstein endorsed (the "innocuous" inverted spectrum hypothesis) is the thin end of the wedge that precludes a Wittgensteinian critique of the kind of inverted spectrum hypothesis he rejected (the "dangerous" kind). The danger of the dangerous kind is that it provides an argument for qualia, where qualia are (for the purposes of this paper) contents of experiential states which cannot be fully captured in natural language. I will pinpoint the difference between the innocuous and dangerous scenarios that matters for the argument for qualia, give arguments in favor of the coherence and possibility of the dangerous scenario, and try to show that some standard arguments against inverted spectra are ineffective against the version of the dangerous scenario I will be advocating. The leading idea of the paper is that an argument for qualia based on spectrum inversion does not require that the inversion be behaviorally indistinguishable. At one crucial point, I will rely on a less controversial version of an argument I gave in Block (1999). Wittgenstein's views provide a convenient starting point for a paper that is much more about qualia than about Wittgenstein.

Functionalism, a philosophical theory, has empirical consequences. Functionalism predicts that where systematic transformations of sensory input occur and are followed by behavioral accommodation in which normal function of the organism is restored such that the causes and effects of the subject's psychological states return to those of the period prior to the transformation, there will be a return of qualia or subjective experiences to those present prior to the transform. A transformation of this type that has long been of philosophical interest is the possibility of an inverted spectrum. Hilary Putnam argues that the physical possibility of acquired spectrum inversion refutes functionalism. I argue, however, that in the absence of empirical results no a priori arguments against functionalism, such as Putnam's, can be cogent. I sketch an experimental situation which would produce acquired spectrum inversion. The mere existence of qualia inversion would constitute no refutation of functionalism; only its persistence after behavioral accommodation to the inversion would properly count against functionalism. The cumulative empirical evidence from experiments on image inversion suggests that the results of actual spectrum inversion would confirm rather than refute functionalism.

Philosophers who advocate the possibility of spectrum inversion often conclude that the qualitative content of experiential states pose a serious problem for functionalism. I argue that in order for the inversion hypothesis to support this conclusion one needs to show that it generalizes to all species of qualia. By examining features of touch, taste, and olfactory sensations, I show there is good reason to resist this generalization, in which case appeals to the possibility of spectral inversion are considerably less effective than they may initially appear.