The real difficulty is that when you combine two sets of preferences, each of which make sense on their own, you get a set of preferences that makes no sense whatsoever: http://plato.stanford.edu/entries/economics/#5.2 https://www.google.com/search?q=site%3Aplato.stanford.edu+social+choice&ie=utf-8&oe=utf-8

There is no easy way to resolve this problem. There is also no known method that takes such an inconsistent set of preferences as input and gives a consistent set of preferences as output such that the output would be recognizable to either party who contributed an original set of preferences as furthering any of their original goals. These random decisions are required so often in cases where there isn't an unanimous agreement that in practice, there would be a large component of arbitrariness every single time CEV tries to arrive at a uniform set of preferences by extrapolating volitions of multiple agents into the future.

This doesn't mean the problem is unresolvable, just that it's an AI problem in its own right, but given these problems, wouldn't it be better to pick whichever Nice Place to Live is the safest to reach instead of bothering with CEV? I say this because I'm not sure Nice Place to Live can be defined in terms of CEV, as any CEV-approved output. Because of the preference aggregation problem, I'm not certain that a world that is provably CEV-abiding also provably avoids flagrant immorality. Two moral frameworks when aggregated by a non-smart algorithm might give rise to an immoral framework, so I'm not sure the essence of the problem is resolved just by CEV as explained in the paper.