Butterfield: the main point of decoherence is that when we model the interaction with the environment, the suppression of superposition [diagonalization] is rapid and inevitable; indeed, which is the selected basis and which correlations are suppressed is not given by the theory and is to some extent a choice in modelling of the system. Sudarsky: true, but there exists contexts [cosmology] where no experimenter and no observer can be associated with that “choice”.