Egan's central mechanism is deceptively simple: a copy of Paul Durham has all his memories, personality, neural architecture.
It is not Paul Durham.
The original experiences the upload as death. The copy experiences continuity—but that continuity is a computational illusion, a consequence of identical mathematical structure, not preserved consciousness.
This is not a philosophical argument about identity. This is a topology problem disguised as metaphysics. When Permutation City was published in 1994, neuroscience had no mechanism for explaining why this mattered — brain tissue was brain tissue, connectionist models existed but remained abstracted.
Twenty-five years later, connectomics revealed that individual identity correlates with structural connectivity patterns, not with any specific neural matter — the brain physically replaces most of its molecular components over years, yet identity persists because the *topology* persists. Egan had encoded this insight into a plot mechanism: personal identity as the shape of the system, not its stuff. What matters is that Egan built identity as a solvable mathematical problem rather than as metaphysical mystery — he didn't guess the answer, but structured the question so only one kind of answer could ever fit.
Read the scene where Paul first encounters his copy in Permutation City (Chapter 5) and reread it after watching the 2018 Connectomics lecture series on identity and neural persistence—specifically the segments on synaptic plasticity and individual variation in brain mapping.
Henry Markram's "The Blue Brain Project: Building a Digital Brain" discusses how connectome data maps individual identity through network topology rather than material composition, which directly parallels Egan's computational model of consciousness.