OK, maybe I went out on a limb with some of my statements about PR. Let me offer a more reasonable rationale for inclduin single-member districts with PR in a bicameral system:
The electorate is made of many group of people, each with their own preferences. It's rare that a single public policy will reflect the first choice of a majority of the voters, but it's possible to come up with policies that at least somewhat satisfy a majority, via compromise. There are 2 ways to find that compromise. The first is that we all indicate our ideal policies, via the proxy of a party (assume that we have a wide range of parties, with diverse platforms, so indicating your favorite party gives an approximate indication of your ideal party preferences). The parties get seats more or less in proportion to how many voters support them, and then the legislators hammer out the compromises via the legislative process. The second is that We the People identify compromises. We do this with a single-winner method that's better than plurality (since plurality makes it almost impossible for more than 2 parties to compete, and hence fails to offer a wide enough range of choices to successfully identify a compromise that satisfies the largest number of voters). I would argue that Approval or Condorcet is the best for that purpose, but that is a point to discuss later. The point is that in each district, we identify the candidate who satisfies the greatest number of voters, and we send him to the legislature. Obviously, single-member districts have their problems, so in a bicameral system the other house should be elected by PR. You could argue for electing both houses by PR, but then the houses are more or less redundant with one another. The largest defect of single-member districts is probably gerrymandering, and that can be fixed: Very large districts and very small districts are difficult to gerrymander. On the very large and very small scales your ability to specifically include or exclude key voter blocs is rather limited. Also, as discussed on this list about a year ago, there are non-partisan districting algorithms that one can use. Let me close with a question: For those who still think single-member districts have no place in a legislature, what do you propose as a good model for a bicameral legislature? Alex ---- Election-methods mailing list - see http://electorama.com/em for list info
