The Nature of Consciousness

In The Singularity Is Near, Ray Kurzweil examines the enduring question of consciousness and its significance given humanity's forthcoming technological advances.

Throughout history, people have wondered why we possess subjective experience through our minds and bodies, our sense of "self." Our scientific inability to fully understand these concepts has fostered beliefs in immaterial souls, though such notions lack empirical support.

The Gradual Replacement Thought Experiment

Kurzweil presents thought experiments to clarify the concept. Consider a biological brain gradually replaced with nonbiological hardware, neuron by neuron. Logically, subjective experience should remain unchanged; I would still be me.

This isn't radical thinking. Our brain's atoms are constantly being replaced anyway; the matter in your brain today is different from the matter that was there a year ago. Identity persists through the pattern of matter and energy defining us, not the specific atoms themselves. We are patterns, not substances.

If the pattern is what matters, then transferring that pattern to a different substrate should preserve identity. Replace neurons with functionally identical artificial neurons, and the subjective experience should continue uninterrupted.

The Copying Problem

The concept becomes complicated when exploring mind copying. A copied mind would think identically to the original and claim identical experiences. From the outside, the copy would be objectively indistinguishable from the original.

Yet if my mind were copied, I would still be experiencing life subjectively through my biological brain. I could not simultaneously be both original and copy. The copy would be convinced it was me, and from its perspective, it would be right. But from my perspective, I would remain here, in this body, looking at a copy that claims to be me.

If mind transfer required destroying the biological original, one might reasonably object. The pattern would be transferred, but would subjective experience transfer with it? Or would it simply end, replaced by a new subjective experience in the copy that believes itself to be continuous with the original?

The Paradox

Here's the paradox: gradual neuron-by-neuron replacement seems intuitively acceptable, but it's functionally equivalent to copying and then destroying the original, just done incrementally. Each replacement is a small copy-and-destroy operation.

So when does subjective experience begin and end? Is there a threshold number of neurons that, when replaced, causes "you" to cease and a copy to take over? That seems arbitrary. But if there's no threshold, then copying should work just as well as gradual replacement.

Why This Matters Now

This question holds immense importance as brain augmentation and mind uploading technologies develop. We are not discussing distant hypotheticals; neural interfaces exist today, and their sophistication is increasing rapidly.

If we are going to merge with our technology (and we are) we need to understand what we're preserving and what we might be losing. The question of consciousness is not merely philosophical; it has practical implications for every decision we make about cognitive enhancement.

I believe that superhuman AI within the next few years will finally answer these ancient questions. We will understand consciousness not through armchair speculation but through building systems that possess it, or that convincingly appear to.

The answer may be uncomfortable. But it will be an answer, grounded in evidence rather than intuition. That alone represents profound progress.