Knowledge Argument - Thought Experiment

Thought Experiment

The thought experiment was originally proposed by Frank Jackson as follows:

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?

In other words, Jackson's Mary is a scientist who knows everything there is to know about the science of color, but has never experienced color. The question that Jackson raises is: once she experiences color, does she learn anything new?

Ontologically, the following argument is contained in the thought experiment:

(P1) Any and every piece of physical knowledge in regards to human color vision has been obtained (by the test subject, Mary) prior to her release from the black-and-white room. She has all the physical knowledge on the subject.

(P2) Upon leaving the room and witnessing colour first-hand, she obtains new knowledge.

(C) There was some knowledge about human colour vision she did not have prior to her release. Therefore, not all knowledge is physical knowledge.

Most authors who discuss the knowledge argument cite the case of Mary, but Frank Jackson used a further example in his seminal article: the case of a person, Fred, who sees a color unknown to normal human perceivers. We might want to know what color Fred experiences when looking at things that appear to him in that particular way. It seems clear that no amount of knowledge about what happens in his brain and about how color information is processed in his visual system will help us to find an answer to that question. In both cases cited by Jackson, an epistemic subject A appears to have no access to particular items of knowledge about a subject B: A cannot know that B has an experience of a particular quality Q on certain occasions. This particular item of knowledge about B is inaccessible to A because A never had experiences of Q herself.