<div>Finally, I come to the end of this series. To conclude, let me return to the initial question which started me down this path: what do the values and heuristics have to say about voting system criteria?</div><div><br>
</div><div>Utility (that is, outcome social utility) is a unique value in that we have a single clear tool for analysis: Bayesian regret simulations. The only two things we need are a model for voter utilities - which should have only weak, linear effects on the performance of a given system - and a model for voter strategy. I hope that my analysis of strategy helps us get the latter. And meanwhile, I hope that the outstanding issues of strategy, along with the issues of expressivity, legitimacy, and cost, can help the partisans of Bayesian regret analysis (a group in which I weakly include myself) be humble about the results so far.</div>
<div><br></div><div>The criteria that relate to expressivity are mainly participation, consistency, and related criteria. There is a certain fundamental tension between expressive freedom and outcome utility in a decisive system. Ballots which give a large degree of decisive freedom to voters inevitably involve strategic tradeoffs between utility and expressivity. Perhaps one way to resolve this is to make a hybrid system, which is part election and part nonbinding poll. The election part would strictly limit voter freedom in order to eliminate strategic concerns; two-rank Bucklin is one possible example of the limited freedom I'm imagining. And the poll part - probably based on Range, for maximum freedom - would allow free expressiveness; while it wouldn't be binding, to keep stratgic concerns from taking over, it would certainly affect a candidate's mandate. The poll would be optional; a simple Bucklin vote would be counted with some default assumptions about what that means in Range terms. Maybe you could even give marginal impact to the poll without making it too strategic. For instance, if you were building a polity from scratch, the rule could be that a Bucklin winner is elected, and if they're also a Range winner they get an extra year on their term; or that the Range winner gets to appoint the attorney general; or some such marginal importance for the poll.</div>
<div><br></div><div>The criteria that relate to legitimacy are participation; consistency; and clone-, strategy-, and fraud- resistance criteria.</div><div><br></div><div>The main criterion that relates to cost is one-round decisiveness.</div>
<div><br></div><div>The heuristics relate to various criteria, but in another sense they function as vague criteria themselves.</div><div><br></div><div>I'll repeat my conclusion to the long section on strategy here, too. Strategy's biggest effects are not on outcome social utility, but on legitimacy and expressivity. I believe that these effects are serious and worth avoiding. Cabal strategy seems to me the best model for strategy analysis, but if it isn't going to get hung up on all Condorcet ties being strategic, it needs to include factors which affect the likeliness of strategy actually being used. These factors include motivation, implied dishonesty, and necessary participation.</div>
<div><br></div><div>Finally, for those who have read through this nearly endless treatise, thank you for your patience. I hope that I've said enough to make it worthwhile. I also hope that I start more than one productive discussion - productive enough to change my mind about some aspects of what I said. My ultimate hope is that this kind of discussion will help us have the perspective to recognize, to design, to evaluate, and finally to begin to agree on the best possible voting systems. The more big-picture perspective we have and share, the more we will become an activist force with which nations must reckon.</div>