  The conventional explanation of delayed-choice experiments appears to violate
our causal intuition at the quantum level. I reanalyze these experiments using
time-reversed and time-symmetric formulations of quantum mechanics. The
time-reversed formulation does not give the same experimental predictions. The
time-symmetric formulation gives the same experimental predictions but actually
violates our causal intuition at the quantum level. I explore the reasons why
our causal intuition may be wrong at the quantum level, suggest how
conventional causation might be recovered in the classical limit, propose a
quantum analog to the classical block universe viewpoint, and speculate on
implications of the time-symmetric formulation for cosmological boundary
conditions.
