[4] The debate that emerged following its publication became the subject of an edited volume, There's Something About Mary (2004), which includes replies from such philosophers as Daniel Dennett, David Lewis, and Paul Churchland.
[7] C. D. Broad, Herbert Feigl, and Thomas Nagel, over a fifty-year span, presented insight to the subject.
The utmost that he could predict on this subject would be that certain changes would take place in the mucous membrane, the olfactory nerves and so on.
Even with the entire physical database at one's fingertips, humans would not be able to fully perceive or understand a bat's sensory system, namely what it is like to "see" the world through sound.
[10] Whether Mary learns something new upon experiencing color has two major implications: the existence of qualia and the knowledge argument against physicalism.
If Mary learns something new upon seeing red, it shows that qualia (the subjective, qualitative properties of experiences, conceived as wholly independent of behavior and disposition) exist.
Specifically, the knowledge argument is an attack on the physicalist claim about the completeness of physical explanations of mental states.
Jacks[11] Jackson believed in the explanatory completeness of physiology, that all behaviour is caused by physical forces of some kind.
These are the two most notable[citation needed] objections to Jackson's thought experiment, and the claim it sets out to make.
Objections have also been raised that, even if Mary's environment were constructed as described in the thought experiment, she would not, in fact, learn something new if she stepped out of her black and white room to see the color red.
"[10] Some philosophers have also objected to Jackson's first premise by arguing that Mary could not know all the physical facts about color vision prior to leaving the room.
Several objections to the argument have been raised on the grounds that Mary does not gain new factual knowledge when she leaves the room, but rather a new ability.
[19] Lewis put forth a similar argument, claiming that Mary gained an ability to "remember, imagine and recognize.
He aims to reinforce this line of objection by appealing to the different locations in which each type of knowledge is represented in the brain, arguing that there is a true, demonstratively physical distinction between them.
[21] By distinguishing that Mary does not learn new facts, simply abilities, it helps to negate the problem posed by the thought experiment to the physicalist standpoint.
For example, Mary could know the fact "red is more like orange than green" without ever experiencing the colors in question.
Gertler uses this disparity to oppose Conee's account: a dualist who posits the existence of qualia has a way of explaining it, with reference to qualia as different entities than physical objects; while Conee describes the disparity, Gertler argues that his physicalist account does nothing to explain it.
Proponents of the old fact/new guise analysis argue that Mary gains a new understanding of an old fact through the acquisition of a phenomenal concept of red.
However, whether this analysis is successful in responding to the knowledge argument depends on how phenomenal concepts are defined in a way that is compatible with physicalism.
Ramachandran and Edward Hubbard of the Center for Brain and Cognition at UCSD argue that Mary might do one of three things upon seeing a red apple for the first time: They explain further: "Which of these three possible outcomes will actually occur?
Much like the theoretical Mary, our colorblind synesthete volunteer cannot see certain hues, because of deficient color receptors.
"[25] Ramachandran and Hubbard's contribution is in terms of exploring "the neural basis of qualia" by "using pre-existing, stable differences in the conscious experiences of people who experience synaesthesia compared with those who do not" but, they note that "this still doesn't explain why these particular events are qualia laden and others are not (Chalmers' "hard problem") but at least it narrows the scope of the problem" (p. 25).
Jackson suggests that Mary is simply discovering a new way for her brain to represent qualities that exist in the world.
In a similar argument, philosopher Philip Pettit likens the case of Mary to patients with akinetopsia, the inability to perceive the motion of objects.
David Chalmers, one of the most prominent contemporary dualists, considers Jackson's thought experiment to successfully show that materialism is false.
Chalmers considers responses along the lines of the "ability hypothesis" objection (described above) to be the most promising objections, but unsuccessful: even if Mary does gain a new ability to imagine or recognize colors, she would also necessarily gain factual knowledge about the colors she now sees, such as the fact of how the experience of seeing red relates to the physical brain states underlying it.