From the Scientific American Magazine December 1995 Issue 

Dancing Qualia in a Synthetic Brain

David J. Chalmers, Australian National University 

Whether consciousness could arise in a complex, synthetic system is a question many people find intrinsically fascinating. Although it may be decades or even centuries before such a system is built, a simple thought experiment offers strong evidence that an artificial brain, if organized appropriately, would indeed have precisely the same kind of conscious experiences as a human being.

   Consider a silicon-based system in which the chips are organized and function in the same way as the neurons in your brain. That is, each chip in the silicon system does exactly what its natural analogue does and is interconnected to surrounding elements in precisely the same way. Thus, the behavior exhibited by the artificial system will be exactly the same as yours. The crucial question is: Will it be conscious in the same way that you are? 




an apple might flash from red to blue.

   Let us assume, for the purpose of argument, that it would not be. (Here we use a reasoning technique known as reductio ad absurdum, in which the opposite hypothesis is assumed and then shown to lead to an untenable conclusion.) That is, it has either different experiences ― an experience of blue, say, when you are seeing red ― or no experience at all. We will consider the first case; the reasoning proceeds similarly in both cases.

   Because chips and neurons have the same function, they are interchangeable, with the proper interfacing. Chips therefore can replace neurons, producing a continuum of cases in which a successively larger proportion of neurons are replaced by chips. Along this continuum, the conscious experience of the system will also change. For example, we might replace all the neurons in your visual cortex with an identically organized version made of silicon. The resulting brain, with an artificial visual cortex, will have a different conscious experience from the original: where you had previously seen red, you may now experience purple (or perhaps a faded pink, in the case where the wholly silicon system has no experience at all).

   Both visual cortices are then attached to your brain, through a two-position switch. With the switch in one mode, you use the natural visual cortex; in the other, the artificial cortex is activated. When the switch is flipped, your experience changes from red to purple, or vice versa. When the switch is flipped repeatedly, your experiences "dance" between the two different conscious states (red and purple), known as qualia.

   Because your brain's organization has not changed, however, there can be no behavioral change when the switch is thrown. Therefore, when asked about what you are seeing, you will say that nothing has changed. You will hold that you are seeing red and have seen nothing but red ― even though the two colors are dancing before your eyes. This conclusion is so unreasonable that it is best taken as a reductio ad absurdum of the original assumption ― that an artificial system with identical organization and functioning has a different conscious experience from that of a neural brain. Retraction of the assumption establishes the opposite: that systems with the same organization have the same conscious experience.

Original Source of this article: Scientific American December 1995 Issue

▷ Chalmers, David J. (1995). The Puzzle of Conscious Experience. Scientific American 273(6), December 1995, pp. 62-68.


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▷ Chalmers, David J. (1995). Facing Up to the Problem of Consciousness. Journal of Consciousness Studies 2(3): 200-219. Reprinted in Stuart R. Hameroff, Alfred W. Kaszniak, & Alwyn C. Scott (eds.) Toward a Science of Consciousness: The First Tucson Discussions and Debates (MIT Press, 1996). Reprinted in Jonathan Shear (ed.) Explaining Consciousness: The Hard Problem (MIT Press, 1997). Reprinted in Rita Carter, Exploring Consciousness (University of California Press, 2002). Reprinted in John Heil (ed.) Philosophy of Mind: A Guide and Anthology (Oxford University Press, 2003). Reprinted without attribution in John R. Vacca (ed.) The World's 20 Greatest Unsolved Problems (Prentice-Hall, 2004). Reprinted in Maureen Eckert (ed.) Theories of Mind: An Introductory Reader (Rowman and Littlefield, 2006).

▷ Chalmers, David J. (1995). Absent Qualia, Fading Qualia, Dancing Qualia. In Thomas Metzinger (ed.) (1995). Conscious Experience. Paderborn: Ferdinand Schöningh / Thorverton, UK: Imprint Academic.

▷ Chalmers, David J. (1995). The Puzzle of Conscious Experience. Scientific American 273(6): 62-68, December 1995. Reprinted in Peter van Inwagen & Dean W. Zimmerman (eds.) Metaphysics: The Big Questions (Blackwell, 1998). Reprinted in Theodore Schick & Lewis Vaughn, Doing Philosophy: An Introduction Through Thought Experiments (Mayfield, 1999). Reprinted in Antonio Damasio (ed.) The Scientific American Book of the Brain (Lyons Press, 2001). Reprinted in Bonnie Beedles & Michael Petracca, Academic Communities/Disciplinary Conventions (Prentice-Hall, 2001). Reprinted in William F. Lawhead (ed.) Philosophical Questions: Classic and Contemporary Readings (McGraw-Hill, 2003). Reprinted in Laurence BonJour & Ann Baker, Philosophical Problems: An Annotated Anthology (Longman, 2004). Reprinted in Brie Gertler & Lawrence Shapiro (eds.) Arguing About the Mind (Routledge, 2007).

▷ Chalmers, David J. (1997). Moving Forward on the Problem of Consciousness. Journal of Consciousness Studies 4(1): 3-46. Reprinted in Jonathan Shear (ed.) Explaining Consciousness: The Hard Problem. (MIT Press, 1997).


▷ Chalmers, David J. (1996). The Conscious Mind: In Search of a Fundamental Theory. Oxford, New York: Oxford University Press. 

▷ Chalmers, David J. (ed.) (2002). Philosophy of Mind: Classical and Contemporary Readings. Oxford, New York: Oxford University Press.

▷ Chalmers, David J. (forthcoming in April 2010). The Character of Consciousness. Oxford, New York: Oxford University Press. 

▷ Metzinger, Thomas (ed.) (1995). Conscious Experience. Paderborn: Ferdinand Schöningh / Thorverton, UK: Imprint Academic. 

▷ Wright, Edmond (ed.) (June, 2008). The Case for Qualia. Cambridge, Massachusetts: MIT Press. 


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