What has become known as Mary’s Room is an allegory devised by Frank Jackson to represent the Knowledge Argument against physicalism. Jackson penned the allegory in 1982 (‘Epiphenomenal Qualia’) and again in 1986 (‘What Mary Didn’t Know’). However the Knowledge Argument predates Jackson’s account, with examples such as that from Thomas Nagel in ‘What Is It Like to Be a Bat‘ (1974), C. D. Broad’s Mathematical Archangel simile (1925), Bertrand Russell’s Blind Man metaphor (1927 – quoted at the bottom of this page), and even Leibniz’s Mill (1714). The following though are the passages concerning Mary’s Room from Jackson’s two articles.
‘ … 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 specialises 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 wave-length combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence ‘The sky is blue’. (It can hardly be denied that it is in principle possible to obtain all this physical information from black and white television, otherwise the Open University would of necessity need to use colour television.)
What will happen when Mary is released from her black and white room or is given a colour television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism is false. Clearly the same style of Knowledge argument could be deployed for taste, hearing, the bodily sensations and generally speaking for the various mental states which are said to have (as it is variously put) raw feels, phenomenal features or qualia. The conclusion in each case is that the qualia are left out of the physicalist story. And the polemical strength of the Knowledge argument is that it is so hard to deny the central claim that one can have all the physical information without having all the information there is to have. …’
– Epiphenomenal Qualia, The Philosophical Quarterly, Vol. 32, No. 127. (Apr., 1982), pp. 127-136.
‘Mary is confined to a black-and-white room, is educated through black-and-white books and through lectures relayed on black-and-white television. In this way she learns everything there is to know about the physical nature of the world. She knows all the physical facts about us and our environment, in a wide sense of ‘physical’ which includes everything in completed physics, chemistry, and neurophysiology, and all there is to know about the causal and relational facts consequent upon all this, including of course functional roles. If physicalism is true, she knows all there is to know. For to suppose otherwise is to suppose that there is more to know than every physical fact, and that is just what physicalism denies.
Physicalism is not the noncontroversial thesis that the actual world is largely physical, but the challenging thesis that it is entirely physical. This is why physicalists must hold that complete physical knowledge is complete knowledge simpliciter. For suppose it is not complete: then our world must differ from a world, W(P), for which it is complete, and the difference must be in nonphysical facts; for our world and W(P) agree in all matters physical. Hence, physicalism would be false at our world [though contingently so, for it would be true at W(P)].
It seems, however, that Mary does not know all there is to know. For when she is let out of the black-and-white room or given a color television, she will learn what it is like to see something red, say. This is rightly described as learning—she will not say “ho, hum.” Hence, physicalism is false. This is the knowledge argument against physicalism in one of its manifestations. …’
– What Mary Didn’t Know, The Journal of Philosophy, Vol. 83, Issue 5 (May, 1986), 291-295.