The inverted spectrum is the hypothetical scenario, pertaining to the philosophy of color, of two people sharing their color vocabulary and discriminations, although the colors one sees—that person's qualia—are systematically different from the colors the other person sees.
Overview
The concept dates back to John Locke.(In this passage, Locke uses "idea" to mean something like "mental image", rather than its modern meaning. He also uses "texture" to mean the physical property that gives rise to a color-sensation) "Neither would it carry any Imputation of Falshood to our simple Ideas, if by the different Structure of our Organs, it were so ordered, That the same Object should produce in several Men's Minds different Ideas at the same time; v.g. if the Idea, that a Violet produced in one Man's Mind by his Eyes, were the same that a Marigold produces in another Man's, and vice versâ. For since this could never be known: because one Man's Mind could not pass into another Man's Body, to perceive, what Appearances were produced by those Organs; neither the Ideas hereby, nor the Names, would be at all confounded, or any Falshood be in either. For all Things, that had the Texture of a Violet, producing constantly the Idea, which he called Blue, and those that had the Texture of a Marigold, producing constantly the Idea, which he has constantly called Yellow, whatever those Appearances were in his Mind; he would be able as regularly to distinguish Things for his Use by those Appearances, and understand, and signify those distinctions, marked by the Names Blue and Yellow, as if the Appearances, or Ideas in his Mind, received from those two Flowers, were exactly the same, with the Ideas in other Men's Minds." Locke, J., 1689/1975, Essay Concerning Human Understanding, Oxford: Oxford University Press. It invites us to imagine two individuals who perceive colors differently: where one person sees red, the other sees green, and vice versa. Despite this difference in their subjective experiences, they behave and communicate as if their perceptions are the same, and no physical or behavioral test can reveal the inversion. Critics of functionalism, and of physicalism more broadly, argue that if we can imagine this happening without contradiction, it follows that we are imagining a change in a property that determines the way things look to us, but that has no physical basis. In more detail:
Metaphysical identity holds of necessity If something is possibly false, it is not necessary It is conceivable that qualia could have a different relationship to physical brain-states If it is conceivable, then it is possible Since it is possible for qualia to have a different relationship with physical brain-states, they cannot be identical to brain states (by 1). Therefore, qualia are non-physical.
The argument suggests that if the inverted spectrum is conceivable, then qualia exist and are non-physical. Some philosophers question the validity of this argument, noting that it involves assumptions about conceivability and possibility.
C. L. Hardin criticizes the idea that an inverted spectrum would be undetectable on scientific grounds:Inverted Qualia, Stanford Encyclopedia of PhilosophyHardin, C. L., 1987, "Qualia and Materialism: Closing the Explanatory Gap", Philosophy and Phenomenological Research, 48: 281-98.
Paul Churchland using the Hurvich–Jameson (H–J) opponent process criticizes the inverted spectrum on scientific grounds:
In some cases, the inverted spectrum scenario may be possible, particularly in a simulated environment. For example, if a world is simulated on a computer and observed through the eyes of one of the characters, it is conceivable that the spectrum of colors could be inverted from the observer's perspective. This could be achieved by making small changes to the code governing how colors are displayed, such that what was previously shown as green might now appear as red, without altering the underlying simulated physics. However, this addresses only the display of colors, not the qualia of the virtual character, if such an agent were capable of having qualia. It is unclear whether such examples from simulations provide evidence for the possibility of inverted spectra in ordinary life.
In his book I Am a Strange Loop, Douglas Hofstadter argues that the inverted spectrum argument entails a form of solipsism in which people can have no idea about what goes on in the minds of others—contrary to the central theme of his work. He presents several variants to demonstrate the absurdity of this idea: the "inverted political spectrum", in which one person's concept of liberty is identical to another's concept of imprisonment; an inverted "sonic spectrum" in which low musical notes sound like "high" ones and vice versa (which he says is impossible because low sounds can be felt physically as vibrations); and a version in which random, complex qualia such as riding a roller coaster or opening presents are reversed, so that everyone perceives the world in radically different, unknowable ways.
Inverted spectrum arguments have applications to behavioralism, physicalism, representationalism, functionalism, skepticism and the hard problem of consciousness.
See also Dualism (philosophy of mind) Functionalism Further facts Mary's room Ontological argument Philosophical zombies Philosophy of color Philosophy of mind Philosophy of perception Physicalism Qualia Subjective character of experience The map is not the territory
Notes
External links Stanford Encyclopedia of Philosophy David Cole