The argument rests on four axioms:
DNA is the blueprint of a conscious, pain-sensitive human organism. Given DNA D and a suitable physical environment, a conscious human H with subjective experience S reliably results:
This is an empirical claim supported by all available biological evidence. Rejecting it requires identifying an alternative mechanism by which conscious observers arise, for which no evidence exists.
The human organism H and its environment U are composed entirely of ordinary physical matter governed by physical laws P. No non-physical process plays any role:
Rejecting this axiom requires positing a non-physical causal influence on biological processes, for which no experimental evidence exists.
The physical processes underlying DNA and the human organism fall within the computable. A sufficiently powerful computing system can, in principle, simulate them to arbitrary precision:
This is a weaker claim than the full Church-Turing thesis: we require only that the specific class of processes DNA relies on is computable, not that all physical processes are. Rejecting this axiom requires identifying a property in DNA that requires infinite precision, for which no evidence exists.
Subjective experience is not epiphenomenal. A human with subjective experience S (for example, pain) behaves differently than the same human without it:
Rejecting this axiom commits one to accepting that subjective experience is causally inert not affecting the behavior of a human.