There is a thought experiment called ‘Mary’s Room.’ It was proposed by Frank Jackson of the School of Philosophy at the Australian National University in 1982.
Mary’s Room is an argument against Physicalism, the belief that all experiences are based on the physical. ‘Life, the Universe, Everything,’ is based on The Laws of Nature.
Mary
Mary lives in a room and has spent her whole life there. The room is painted black and white. No colors at all. Her skin is black, her eyes are grey, and her hair is all white. Her clothing is all stylishly presentable in a spectrum from cold black to radiant white. She has one way to communicate with the outside world, which is a computer screen, also black and white.
Mary is a brilliant woman. In fact, she is the most brilliantly intelligent woman ever. Inside her room are libraries containing all the knowledge that all people know, have known, or will ever know. In fact, her library contains all knowledge that exists, existed, or that will ever exist everywhere and anywhere and she learns it all and understands it all perfectly. She can communicate with the outside world to share her experiences, ask questions, and gain more insights.
One branch of knowledge is color.
Mary’s Knowledge
She learns about the different wavelengths of the electro-magnetism that makes up the rainbow. Certain bands of wavelengths are called different things. These are called X-rays. Those are called radio waves. These other are called red, green, and blue. The last three are very tiny slivers on a very long spectrum.
Mary learns about the eye, how it has rods and cones in the retina on the back of the eyeball. How the cones have filters on them that only let certain wavelengths of radiation through. These correspond to the groupings called red, green, and blue mentioned above. How a photon of light will strike a cone and, if it is in the right wavelength range, will pass through the filter, then it will strike light sensitive molecules. The molecules don’t know that the photon hitting them is red or green or blue, they only sense the photon that makes it through the lens. A molecule absorbs a photon, is excited into a different energy state, and behaves accordingly.
The cones then experience a Rube Goldberg cascade of molecular seesaws, binding and unbinding, electron exchanges, and really clever gymnastics causing proteins to flex or bunch up. The result is a stream of sodium ions carrying a charge through a long strand of optic nerve. At the end it is channeled to a certain part of the brain called the visual cortex.
At the visual cortex a machine will detect the signal coming in. There are three nerve fibers attached to one machine, each originates in one red, green, or blue cone. The signals all look the same, they are identical. The machine doesn’t know what red, green, or blue are. Only that the signals came through specific fibers labeled ‘red,’ ‘green,’ and ‘blue.’ They could be labeled 1, 2, and 3; x, y, and z; or Larry, Curley, and Moe. They are then sent further into the visual cortex where they are gathered and amplified.
The brain interprets this galactic pattern of grey signals as colors, shapes, images, moving kaleidoscopes and ultimately, as vision.
The same signals are sent to different parts of the visual cortex. This part just registers colors. That’s all it does. It sits there all day and says, ‘This signal is red. That signal is green. The one over there is blue.’
Over here another part is just registering edges. ‘Here is a sharp divide between a light area and a darker area, there is a fuzzy one.’
And over here it is just finding shapes, ‘Here is a triangle. There a square. Over here a circle.’
Mary’s Experience
One day Mary finds a door she had not noticed before. She opens it. Walks through. And out into the light.
“Woah!” she exclaims. A sunset filled sky is before her. Stunned, she watches until the colors, the reds, yellows, oranges, shreds of black and brown and occasional blues and deep purples, sink into the horizon, flicker, dim, and go out.
She contemplates what she just felt.
“Felt!” she thinks. “I have never tasted that word before.”
Until now words like red, feel, sense, and experience had been abstractions. Even the word ‘abstraction’ was only an abstraction. Now they had a new feel to her. A new ‘taste’ as she put it.
She walks along a path toward the dying sunset, thinking. Then she pauses. Stops. Her head trembles. And she looks up.
“Wait,” she says. “I wonder what sex feels like?”
