When we see, hear, smell, or feel something, what’s happening? How do we take in information about the world around us, and how does that information get to us?
When I smell the fragrance of new azalea blooms in my yard, actual microscopic particles emanating from the blooms themselves are wafting through the air, entering my nose, and interacting with my olfactory cells. Anytime you smell anything, there’s physical contact in the form of floating particles occurring between you and the source of the smell.
Even more remarkably, if I see a rabbit busily investigating some sprouts in my neighbor’s garden, physical sub-atomic particles called photons have actually interacted with that physical rabbit over there and then have physically entered through my eye’s cornea and lens, finally interacting with photoreceptor cells at the back of my eye. Whenever you see something, you’re physically interacting with sub-atomic particles that have already interacted with the object of your vision.
Hearing involves the vibration of air molecules in your ear physically set in motion by whatever made the sound. Touch is when the outermost atoms on your skin meet the outermost atoms on another surface and are finally repelled by the mutual negative charges in the electron clouds of those atoms. This means that you technically never really touch anything directly, but you can still feel those electron repulsion forces through your nerve receptors as the sensation of pressure and texture. This atomic interaction is still a physical reality, though, and if you haven’t guessed it yet, the point I’m trying to make is that our entire sensory experience of the world is physical, dealing with matter. It’s not only touch that puts us in physical contact with other things: sight, smell, and hearing do, too.
That’s how information gets to us from outside, but what happens to that information once it reaches us? In every one of those cases, those molecules, atoms, and sub-atomic particles are converted into electrical signals that travel through our nerves and into our brain. Once in our brain, those signals reach their destinations in the neural cells to which those nerves led. Odiferous particles, vibrating air molecules, photons traveling at different wavelengths — they all end up as electrical signals terminating in our neurons. And those electrical signals, those nerve bundles, and those neurons are all also physical things. The entire system of sensory information, from the outside world to the inner brain, is physical and spectacularly convertible from one type of physical reality to another. But there’s one more step of conversion for the information to undergo: interpretation.
Here’s where physicality lets us down. We experience these terminating electrical signals as qualia, the “internal and subjective component of sense perceptions, arising from stimulation of the senses by phenomena” (Oxford Dictionary). In layman’s terms, unconscious matter is somehow turned into a subjective experience. Remarkable advances in brain imaging have shown us unprecedented detail in regional brain activity triggered by different kinds of thinking and phenomenal input, but it hasn’t shown us the locus of consciousness that interprets that activity. And it never will. Clearly, there’s a correlation between conscious thought and measurable brain activity, but correlation and causation are radically different things, and one could just as easily (and defensibly) argue that rather than our brain creating consciousness, consciousness makes use of the physicality of the brain.
But before we even get to that point, all we really need to do to demonstrate consciousness is not a physical reality is to examine just what physical reality is: it’s brute, undirected, unconscious. Matter has no meaning, no apparent purpose, and no intentionality. It doesn’t know anything, desire anything, or experience anything. But we do. We as selves intend and interpret. We not only sense and react to phenomena (as other life forms surely do as well), but we translate those sensations into qualia experienced by a subjective “I”. Some dogmatically committed naturalists think that our sense of being a subject is only an illusion, noting correctly that a single locus of consciousness inside the head “makes no neuro-anatomical sense.” But non-naturalists are free to explore the fascinating correlation between consciousness and brain matter without struggling with the problem of the “place” in the brain where consciousness happens. And if consciousness is only an illusion, who exactly is perceiving that illusion? Without a subjective perspective to experience it, what precisely does the word “illusion” even mean?
Speaking of the meaning of words—meaning, concepts, and words are also indicative of a decidedly non-material quality of consciousness: that of semantic content. Just like calculators don’t know the meaning of the number 8, and computers don’t understand the concept of a “file”, the human brain in its mere physicality could never assign meaning to the electrical signals lighting up its neurons. The structure of the brain is physically capable of spectacularly converting photons’ interactions with photo-receptor cells and the resulting electrical signals transmitted via optical nerves into a vastly different final arrangement of terminating electrons, but only a non-material conscious self could “recognize” that final electrical rorschach as a rabbit in a vegetable garden. Material nature is incapable of semantic content; only consciousness can build a calculator, program a computer, or see a rabbit.
So does consciousness interact with the physical world? Yes. Can we even affect consciousness by messing with the physical apparatuses it makes use of in the brain? Yes. But is consciousness reducible to physicality? Most certainly it is not. No advancement in science will ever show otherwise, moreover, because it’s not a matter of the quantity of research that has been done on the subject that has prevented this, but a matter of the quality of consciousness itself. It is simply wholly other than matter. It’s not a difference in degree that separates matter from the mystery of consciousness. It’s a difference in kind.