  Counterfactual communication protocols are analysed using three approaches: a
classical argument, the weak trace criterion, and the Fisher information
criterion. It is argued that the classical analysis leads to contradiction and
should therefore be abandoned. The weak trace and Fisher information criteria
are shown to agree about the degree of counterfactuality of communication
protocols involving postselection. It is argued that postselection is a
necessary ingredient of counterfactual communication protocols. Coherent
interaction experiments, as well as a recently introduced modification of
counterfactual communication setups which eliminates the weak trace, are
discussed.
