For some reason, Mary’s room has been garnering attention lately. This TED Ed video on it was shared on Aeon’s site this week.
The wording of the actual thought experiment is important, so quoting Frank Jackson’s words (via the Wikipedia article on the knowledge argument):
Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white television monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like “red”, “blue”, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal cords and expulsion of air from the lungs that results in the uttering of the sentence “The sky is blue”. … What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not?
If we take the phrase “all the physical information there is to obtain” literally, then Mary knows not only the facts relayed above, but every effect the stimulus will have on a human nervous system, including her own, every affective reaction, every association that will be triggered, both conscious and unconscious, every memory, every physiological reaction, as well as all their downstream effects. This might include Mary simulating the effects on her own nervous system without photons of the relevant wavelength ever striking her retina.
In other words, if physicalism is true, then Mary’s complete knowledge of all the physical facts will include knowledge of what it is like to experience color. When she does have the actual experience for the first time, there should be no surprises. If there are, then she didn’t really have all the physical facts.
On the other hand, if some form of dualism is true, then the physical facts are not all the facts, and she probably does learn something with the experience. But the thought experiment, like most philosophical thought experiments, doesn’t demonstrate that one way or another. It only flushes out our intuitions about the situation.
Of course, many might say it’s implausible for Mary to have such thorough, pretty much omniscient, knowledge of the experience of color prior to the experience. And they’d be right. But if we’re going to take the premise seriously, that’s what it entails.
Unless of course I’ve missed something?