  Recently, several authors have criticized the time-symmetrized quantum theory
originated by the work of Aharonov et al. (1964). The core of this criticism
was a proof, appearing in various forms, which showed that the counterfactual
interpretation of time-symmetrized quantum theory cannot be reconciled with
standard quantum theory. I argue here that the apparent contradiction is due to
a logical error. I analyze the concept of counterfactuals in quantum theory and
introduce time-symmetrized counterfactuals. These counterfactuals do not lead
to any contradiction with the predictions of quantum theory. I discuss
applications of time-symmetrized counterfactuals to several surprising examples
and show the usefulness of the time-symmetrized quantum formalism.
