Chapter 11

The Identical Replica

Let's make this concrete with a thought experiment.

Imagine that advanced technology creates an identical replica of you (what I call an identireplica in the full theoretical framework), an exact physical replica of your entire body, down to the atomic level. Every cell, every protein, every neural connection, every chemical concentration is identical. This replica is placed in an identical environment.

The replica behaves exactly like you. It has your memories. It speaks like you, moves like you, thinks like you. If you ask it questions about your life, it answers correctly, not because it has been programmed with your biography, but because it has your brain, with your neural connections that encode your memories.

Here is where most people hesitate. Their instinct says no — that's a copy, not me. But examine that instinct carefully. What exactly would be different about the replica's experience? It has your memories of your childhood and remembers reading this book. It feels like itself, like you, because its brain is producing the same ixperiencitness (recall: the quality of subjective experience that makes it yours, the "you-ness" of consciousness) as yours.

The objection that it's "just a copy" assumes that something about your specific atoms, beyond their arrangement and functioning, contributes to your consciousness. But as we established in Part One and Part Two, the evidence consistently points the other way.

The "It's Not Me" Response Revisited

When people say "a replica is not me," they are usually imagining the original and the replica existing side by side. Two bodies in the room, both claiming to be the same person. Surely only one can be "real."

But the correct analysis is subtler. Both you and the replica have identical ixperiencitness at the moment of creation. There are not two different conscious experiences happening; there are two instances of the same conscious experience, produced by two different physical systems — like lighting a second candle from the flame of the first.

From the moment of creation onward, the two instances will diverge as they receive different sensory inputs. But the ixperiencitness, the deep quality of "you-ness," remains the same even as the specific content of consciousness diverges.

Why This Matters for Immortality

The identical replica thought experiment matters because it establishes a key principle: your conscious experience can be produced by a body other than your current one.

If this principle is accepted, then the barrier to immortality falls. Death destroys one body, but it does not destroy the possibility of another body producing the same ixperiencitness. And wherever and whenever that ixperiencitness is produced, you are there. You are experiencing it. You are alive.

This is not resurrection or an afterlife. It is the logic of structure and functioning, applied consistently. (If you find yourself reaching for objections about causal continuity, about what makes the "original" special, about whether this is really testable — hold that thought. Part Four is devoted entirely to engaging the strongest counterarguments.)

Read the rest of this chapter

The remaining text (examples, counter-arguments, and longer connective passages) is in the book.

Get the Book All chapters