Many paradoxes have been revealed in the theory of democracy over the years. This article points to yet another paradox at the heart of democracy, whether in its aggregative or deliberative form.The paradox is this: If you are dealing with a large and heterogeneous community, in which people's choices are menu-sensitive in diverse ways, and if people's cognitive capacities preclude them from considering all items on a large menu simultaneouslythen individuals’ choices may be unstable and manipulable depending on how choices (...) over cognitively-manageable subsets of the menu are partitioned and sequenced, 1 and the collective choice may be likewise unstable and manipulable in consequence.Aggregative democracy casts this argument in terms of ‘alternatives’ on the menu for choice. Deliberative democracy casts this argument in terms of ‘considerations’. The same formal problem arises in both cases. (shrink)