A brilliant neurophysiologist, Mary, knows all there is to know about her academic specialty, the science of vision: the physics, biology, chemistry, physiology, and neuroscience. Also how we see colour.Can we fully understand the world through thought and language—or do we only really understand it through experience? And if only through experience, can we truly communicate with one another on every level? These were some of the questions which lay behind a famous thought experiment of 1982:
There’s a catch, however: Mary has lived her entire life in a totally black-and-white room, watching a black-and-white screen, and reading black-and-white books. An entirely monochromatic existence. Then, unexpectedly, her screen reveals a bright-red tomato.
What was it like for Mary to experience colour for the first time? Or as the Australian philosopher Frank Jackson asked, who originated this thought experiment, ‘Will [Mary] learn anything or not?’ *
Jackson’s original takeaway from his scenario was that Mary’s first-time experience of red amounted to new knowledge—despite her comprehensive scientific knowledge in the field of colour vision. Jackson believed at the time that colour perception cannot entirely be understood without a person visually experiencing colour.
However, not everyone agreed. Some proposed that Mary’s knowledge, in the absence of first-hand experience, was at best only ever going to be partial, never complete. Indeed, renowned philosopher Thomas Nagel, of ‘what is it like to be a bat’ fame, was in the camp of those who argue that some information can only be understood subjectively.
Yet, Mary's complete acquaintance with the science of vision might well be all there is to understanding the formation of knowledge about colour perception. Philosopher and neurobiologist Owen Flanagan was on-board, concluding that seeing red is a physical occurrence. As he put it, 'Mary knows everything about colour vision that can be expressed in the vocabularies of a complete physics, chemistry, and neuroscience.
Mary would not have learned anything new, then, when the bright-red tomato popped up on her screen. Through the completeness of her knowledge of the science of colour vision, she already fully knew what her exposure to the red tomato would entail by way of sensations. No qualities of the experience were unknowable. The key is in how the brain gives rise to subjective knowledge and experience.
The matter boils down to whether there are nonphysical, qualitative sensations—like colour, taste, smell, feeling, and emotion—that require experience in order for us to become fully familiar with them. Are there limits to our comprehension of something we don’t actually experience? If so, Mary did learn something new by seeing red for the first time.
A few years after Frank Jackson first presented the ‘Mary’s room’ thought experiment, he changed his mind. After considering opposing viewpoints, he came to believe that there was nothing apart from redness’s physical description, of which Mary was fully aware. This time, he concluded that first-hand experiences, too, are scientifically objective, fully measurable events in the brain and thus knowable by someone with Mary’s comprehension and expertise.
This switching of his original position was prompted, in part, by American philosopher and cognitive scientist Daniel Dennett. Dennett asserted that if Mary indeed knew ‘absolutely everything about colour’, as Jackson’s thought experiment presumes, by definition her all-encompassing knowledge would include the science behind people’s ability to comprehend the actual sensation of colour.
To these points, Mary’s factual expertise in the science of colour experience—and the experience’s equivalence and measurability in the brain—appears sufficient to conclude she already knew what red would look like. The experience of red was part of her comprehension of human cognitive functions. Not just with regard to colour, but also to the full array of human mental states: for instance, pain, sweetness, coldness, exhilaration, tedium—ad infinitum.
As Jackson ultimately concluded, the gist is that, given the special particulars of the thought experiment—Mary acquired ‘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 and blue’—Mary did not acquire new information upon first seeing the red tomato. She didn’t learn anything. Her awareness of redness was already complete.
* Frank Jackson, 'Epiphenomenal Qualia', Philosophical Quarterly, 32, April 1982.
