The ocean's deepest point is in a small valley in the Mariana Trench, southwest of Guam. Any science enthusiast, geography student, or trivia whiz can tell you as much. We’ve explored the ocean's depths and the expanses of space, the highest mountains, and the lowest valleys—but there’s one thing we just can’t seem to understand, and it’s right above our noses. The brain, that fatty wrinkled organ covered in blood vessels, nerves, and neurons, remains one of humanity's greatest mysteries. It’s a computer built by evolution, whose programming we don’t yet understand.
The brain sends and receives chemical and electrical signals from the body in a complex communication process. A widely accepted doctrine known as physicalism reaffirms this, maintaining that neural activity can be attributed to physical states. But how can we be sure of this? Are there things beyond the physical realm that facts can’t fully explain, and if so, does recreating a physical state necessarily create a corresponding mental state, or are the building blocks of our mind just that, building blocks?
Imagine a brilliant scientist named Mary who lives in a small monochrome room with no doors or windows for her entire life. She spends her time reading books and watching a colorless computer monitor at the center of the room. During her confinement, Mary specializes in neurophysiology, or the study of vision. She knows everything, from the reflection of light through the cornea, the pupil, the lens, and the retina to every one of its two million working parts. One day, her computer monitor malfunctions, displaying the image of an apple in full color. If Mary already knows everything about color and how it’s perceived, will she learn anything more from observing it?
Modern philosophers argue that some qualities are only discoverable through experience. Contradicting the theory of physicalism, thinkers like Thomas Nagel and Christopher Peacocke think that there are intangible properties that can’t be quantified yet affect us just the same. Such properties are called qualia, and they are unique to the person experiencing them and cannot be quantitatively measured. These theorists speculate that if an advanced computer system were to recreate someone's brain down to each atom in a mirror configuration, it would not have the same thoughts. The principle remains with color vision and many other individual perceptions, which contain indescribable qualities that transcend physical descriptions. Some philosophers doubt this conclusion, arguing that if Mary knows everything there is to know about color vision, then she will have understood what it would look like without seeing it.
Is our reality defined by experience, knowledge, or a combination of both? We may never know. After all, if something can only be understood if experienced, then we’ll just have to wait and see.
