Post Author: Bill Pratt
If you are a materialist, physicalist, or naturalist, then you must say “yes” because everything reduces to physical processes on those views. Francis Parker, Professor of Philosophy at Haverford College, argues, however, that the act of knowing cannot be a physical process.
Parker offers the following scenario that a materialist may offer for how a person would know the contents of a book:
First of all, there is the book—a real, physical thing existing in a certain definite spatial location. Then there is the light reflected from this book, waves or particles (or “wavicles”) of light passing from the surface of the book to your eye. Upon reaching your eye, you may continue, these particles of light pass through the cornea, aqueous humour, lens, and vitreous humour and then strike the nerve-endings in the retina where they produce an electrochemical impulse. This impulse, you may then say, travels along the optic nerve to the occipital lobe of the brain in the back of your head, whereupon, finally, you say you “see” the book. Thus awareness, you may suggest, is merely a straightforward physical process, just like any other.
After this account of knowing the book, Parker asks, “Where is the object of your knowledge? Where is the book you see?” If the materialist eagerly offers, “The book is out there, in space, where we see it,” this presents a problem.
Parker walks us through the problem the materialist now faces.
Let us look once more at the process involved. The seeing of the book requires all of the steps enumerated above. You do not see the book until after all these steps have occurred, until the end of the process. And when the process is completed, the earlier stages no longer exist. But where is the end of this process? In the back of your brain. Hence it would appear that the physical thing that you physically see is not “out there,” separate from you in space, but rather in your head—”under your hat.” And for this reason this materialistic account of the act of knowing has sometimes been called the “under-the-hat” theory.
So if knowing is a physical process, then the object we know is actually not “out there” but in our brain where the visual process ends. This seems like a strange result. If knowing is a purely physical process, then the objects of our knowledge only exist spatially in our brain. We don’t know anything at all outside of our brains.
Is this what materialists want to sign up for? Part 2 of this post will uncover more problems for the materialist account. Stay tuned…