On Mary the super-scientist

Consider the following scenario:

Mary is a neuroscientist who lives in a black and white room and has only ever experienced the world in black and white. As an expert in color vision and perception, she knows everything about its physics and biology, including how light of different wavelengths stimulate the retina of the eye, how it triggers electrical signals, and how the brain interprets these signals as millions of colors.

One day, her black and white computer screen malfunctions and she sees a red apple for the first time. Does she learn anything new as a result of this experience?

Many of us intuitively assume that the experience of seeing color for the first time is vastly different from understanding it theoretically. However, the answer to this question is not that simple. This thought experiment, also known as the knowledge argument, has been the subject of debate for decades.

Philosopher Frank Jackson, who proposed the original thought experiment, argued that although Mary had knowledge of all the physical facts about color vision, experiencing color taught her something new. Therefore, mental states such as color perception cannot be fully explained by physical facts alone. There must be non-physical properties and knowledge which can only be discovered through conscious experience. Jackson's argument was against physicalism, the view that only physical things exist in the universe and that all knowledge is physical knowledge.

Here are the most common responses to the thought experiment:

  • Some argue that if Mary’s knowledge of color vision were truly comprehensive, she would be able to imagine and experience the same mental state that would be produced by actually seeing color. If that were the case, she would already know what it’s like to experience color and therefore learn nothing new.
  • Others argue that her knowledge was incomplete due to the limitations of human language, rather than her lack of supposed non-physical knowledge that can only be gained through experience.

I find the last argument quite compelling. It is possible, even likely, that our ability to communicate knowledge is severely limited by language, given that written language is a relatively new phenomenon, only about 6,000 years old. With advanced language thousands of years from now, it might actually be possible for Mary to learn and know what it’s like to experience color without ever experiencing it herself.

Why does any of this matter? It highlights the inherent difficulty of understanding the mind from within the mind. More importantly, it raises an interesting question: are there fundamental limits to what we can know about something we cannot experience, or will the scientific pursuit of knowledge help us overcome our limitations?

If you’re interested in exploring this thought experiment further, check out this great short video from TedEd:

Side note: This probably requires its own blog post, but I noticed similarities with cognitive scientist John Vervaeke’s concept of the four kinds of knowing: propositional, procedural, perspectival, and participatory. Specifically, perspectival knowing is distinct from knowing a fact like 2+2=4. It is based on knowing what it is like to be, and comes from presence. This seems to support the idea that there was a distinct change in Mary’s knowledge before and after experiencing color.