Imagine some beings much like ourselves, but which are unable to dissemble. What exactly would be lost if we were such beings? Why, in other words, have we developed as dissemblers as opposed to non-dissemblers? I will argue that, given some plausible assumptions about our epistemic and psychological limitations, one important thing that would be lost would be our capacity for social repair---or at least much of it. On one plausible understanding of the functions of our capacities, then, the function of deception turns out not to be anything selfish, but rather something like social stability.