Comment by glenweyl

This is a great question and one of the central ones my analysis addresses (http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2264245). You can read the results in details for the general guarantees, but a few observations about the scenario you describe. First, doubling group size at worst increases by a factor of the square root of two the number of votes you can buy with the same amount of money. To double the votes you buy you would have to increase aggregate expenditures by the square root of two as well. Second, I disagree that these coalitions would be stable. If you gave someone $35 million, why wouldn't they just keep the full $35 million? Under 1p1v there is no incentive to cheat on the coalition...you get to keep your money regardless. Under QV there is a huge incentive to cheat on the coalition and it could be made even larger by giving bounties for ratting out to the police, which has been extremely effective in antitrust in breaking cartels. In fact the situation is extremely analogous to antitrust. Cartels do harm market performance, but I think few of us would, as a result of them, prefer rationing over markets.