  David Mermin's recent paper with the same title as this one makes it clear
that his claim to have found a gap in my reasoning rests on his claim that my
argument violates a criterion for meaningfulness of counterfactual statements
that I myself had set down. I set down no such requirement. But I am willing to
accept it as a conservative sufficient condition. This already entails, within
my proof, that nature must have a deep structure that extends beyond what
actually occurs. It imposes, without appeal to the notion of determinism or
hidden variables, constraints connecting, at the macroscopic level, what did
occur to what would have occurred if certain quantum choices had gone
differently. All the statements in the proof have natural meanings within the
context of an examination of that deep structure.
