Originally written January 13, 2002. Published at Edge and published on KurzweilAI.net January 14, 2002.

Perhaps I am this stuff here, i.e., the ordered and chaotic collection of molecules that comprise my body and brain.

But there’s a problem. The specific set of particles that comprise my body and brain are completely different from the atoms and molecules than comprised me only a short while (on the order of weeks) ago. We know that most of our cells are turned over in a matter of weeks. Even those that persist longer (e.g., neurons) nonetheless change their component molecules in a matter of weeks.

So I am a completely different set of stuff than I was a month ago. All that persists is the pattern of organization of that stuff. The pattern changes also, but slowly and in a continuum from my past self. From this perspective I am rather like the pattern that water makes in a stream as it rushes past the rocks in its path. The actual molecules (of water) change every millisecond, but the pattern persists for hours or even years.

So, perhaps we should say I am a pattern of matter and energy that persists in time.

But there is a problem here as well. We will ultimately be able to scan and copy this pattern in a at least sufficient detail to replicate my body and brain to a sufficiently high degree of accuracy such that the copy is indistinguishable from the original (i.e., the copy could pass a “Ray Kurzweil” Turing test). I won’t repeat all the arguments for this here, but I describe this scenario in a number of documents including the essay “The Law of Accelerating Returns” (see The Law of Accelerating Returns).

The copy, therefore, will share my pattern. One might counter that we may not get every detail correct. But if that is true, then such an attempt would not constitute a proper copy. As time goes on, our ability to create a neural and body copy will increase in resolution and accuracy at the same exponential pace that pertains to all information-based technologies. We ultimately will be able to capture and recreate my pattern of salient neural and physical details to any desired degree of accuracy.

Although the copy shares my pattern, it would be hard to say that the copy is me because I would (or could) still be here. You could even scan and copy me while I was sleeping. If you come to me in the morning and say, “Good news, Ray, we’ve successfully reinstantiated you into a more durable substrate, so we won’t be needing your old body and brain anymore,” I may beg to differ.

If you do the thought experiment, it’s clear that the copy may look and act just like me, but it’s nonetheless not me because I may not even know that he was created. Although he would have all my memories and recall having been me, from the point in time of his creation, Ray 2 would have his own unique experiences and his reality would begin to diverge from mine.

Now let’s pursue this train of thought a bit further and you will see where the dilemma comes in. If we copy me, and then destroy the original, then that’s the end of me because as we concluded above the copy is not me. Since the copy will do a convincing job of impersonating me, no one may know the difference, but it’s nonetheless the end of me. However, this scenario is entirely equivalent to one in which I am replaced gradually. In the case of gradual replacement, there is no simultaneous old me and new me, but at the end of the gradual replacement process, you have the equivalent of the new me, and no old me. So gradual replacement also means the end of me.

However, as I pointed out at the beginning of this question, it is the case that I am in fact being continually replaced. And, by the way, it’s not so gradual, but a rather rapid process. As we concluded, all that persists is my pattern. But the thought experiment above shows that gradual replacement means the end of me even if my pattern is preserved. So am I constantly being replaced by someone else who just seems a like lot me a few moments earlier?

So, again, who am I? It’s the ultimate ontological question. We often refer to this question as the issue of consciousness. I have consciously (no pun intended) phrased the issue entirely in the first person because that is the nature of the issue. It is not a third person question. So my question is not “Who is John Brockman?” although John may ask this question himself.

When people speak of consciousness, they often slip into issues of behavioral and neurological correlates of consciousness (e.g., whether or not an entity can be self-reflective), but these are third person (i.e., objective) issues, and do not represent what David Chalmers calls the “hard question” of consciousness.

The question of whether or not an entity is conscious is only apparent to himself. The difference between neurological correlates of consciousness (e.g., intelligent behavior) and the ontological reality of consciousness is the difference between objective (i.e., third person) and subjective (i.e., first person) reality. For this reason, we are unable to propose an objective consciousness detector that does not have philosophical assumptions built into it.

I do say that we (humans) will come to accept that nonbiological entities are conscious because ultimately they will have all the subtle cues that humans currently possess that we associate with emotional and other subjective experiences. But that’s a political and psychological prediction, not an observation that we will be able to scientifically verify. We do assume that other humans are conscious, but this is an assumption, and not something we can objectively demonstrate.

I will acknowledge that John Brockman did seem conscious to me when he interviewed me, but I should not be too quick to accept this impression. Perhaps I am really living in a simulation, and John was part of the simulation. Or, perhaps it’s only my memories that exist, and the actual experience never took place. Or maybe I am only now experiencing the sensation of recalling apparent memories of having met John, but neither the experience nor the memories really exist. Well, you see the problem.

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