Today, in one of my classes at school, I taught my students about the theme of “Death and Immortality,” including a famous philosophical thought experiment: Mary’s Room.
I’ve known about this thought experiment for many years, and I even quoted it in one of my books. But explaining it again today still gave me goosebumps, because this thought experiment reveals the possibility of mind–body separation—it suggests that human consciousness may indeed have a non-physical aspect, and that human experience may not be fully explainable in terms of purely physiological phenomena. This possibility deeply shook me.
There are several versions of Mary’s Room. Let’s look at one of them:
Mary is a neuroscientist in the future, and her field of research is color vision. In her era, science is highly advanced, and neuroscience has achieved a completely thorough understanding of the physiology of color vision. So Mary knows all the physiological and psychological facts about color and color vision (please note: all of them).
The irony, however, is that Mary is congenitally color-blind. She knows everything there is to know about color, but she cannot experience color. One day, a surgery that can restore color vision becomes available. After the operation, the moment the bandages are removed from her eyes, the first thing Mary sees is a bouquet of roses in the room. This is the first time she has truly seen red; only then does she finally understand what red actually looks like to the eye.
Clearly, this experience makes Mary realize that there are things about color and color vision that she did not previously understand.
But here’s the contradiction: before she saw red, she supposedly already knew every fact related to color.
In other words, what it feels like to see red has absolutely nothing to do with any physical, objective fact that produces this feeling!
That’s right: for a person to see red, photons of a particular wavelength must strike the retina, after which the optic nerve and visual cortex carry out a series of processes. But none of these objective facts can describe the experience of seeing red itself.
For someone like me, who was steeped in materialism from childhood, this is a truly terrifying conclusion to think through! From a strictly materialist worldview, everything in the subjective world is merely a shadow cast by the objective world. All your ideas, thoughts, and feelings can ultimately be reduced to biochemical and neural activity in the brain.
But Mary’s Room suggests another possibility: conscious experience at the mental level cannot simply be equated with neural and biochemical processes at the physical level. Although subjective experience corresponds one-to-one with its objective material basis, the two belong to two completely different worlds.
Consciousness has always been the psychology topic that fascinates me most. Of course, the mystery of consciousness is also one of the deepest ultimate puzzles in the world. I’ll keep discussing this subject with you all in the future.
Note
- The articles in this “New Insights in Psychology” series were short popular-science pieces and casual reflections written at the time to accompany content related to Zhichao Wei: New Insights in Psychology. They were published on the now-closed platform Fàntuán, and the original link no longer exists.
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