Mary is a brilliant scientist who specialises in colour. She knows everything about colour – the spectrum, wavelengths, properties of light, the mechanism of how human vision works… She knows exactly how a certain wavelength of light will excite the retina and what kind of electrical impulse it will send in the brain. However, Mary has never seen colour. She has lived all of her life in a black and white room and can only observe the world through a black and white TV screen. The question is: if Mary was to leave the room and see the colourful world for what it is, would she learn something new?
Considering that Mary already knows everything theoretical about colour, would her seeing colour change anything? Or is the experience of seeing a colour something that you cannot learn without actually experiencing it?
This was a thought experiment proposed by Frank Jackson to question the nature of knowledge. Is physical knowledge truly everything, or is there something more than that? In philosophy, there is a concept called qualia, which describes the subjective, qualitative properties of experiences. That is, experience is a unique type of knowledge that cannot be learnt without experiencing it first-hand.
A further expansion of this idea is the refutation of physicalism – the school of thought that argues that everything (including knowledge and the mind) is physical. The logic is that since Mary knew everything “physical” about colour before leaving the room, her learning “something’ (i.e. experience of colour) is a direct argument against all knowledge being physical, as she learnt something “new”.
Another way to look at it is this. Some things in life can only be learnt through experiencing it. It is not enough trying to learn about life and the world purely from stories and books. To truly learn everything, you must get out there and experience it yourself.