--- On Mon, 7/28/08, Chris Benham <[EMAIL PROTECTED]> wrote: > From: Chris Benham <[EMAIL PROTECTED]> > Subject: Re:RELEASE: Instant Runoff Voting > To: "EM" <election-methods@lists.electorama.com> > Cc: [EMAIL PROTECTED] > Date: Monday, July 28, 2008, 9:57 AM > Aaron, > "In an important respect, Condorcet is more natural > than IRV: if a majority prefers Brad over Carter, this > preference exists whether the voting system does anything > with it, or even elicits enough information to determine > that it exists. " > Yes, except that "Condorcet" is a criterion and > IRV is a method, and "more natural" doesn't > have a precise meaning. >
I think the meaning of "more natural" was sufficiently clarified by my explanation, namely that Condorcet methods are based on a property that exists in the preferences themselves, rather than being an artifact of the counting rules. Which is why there can be such a thing as a Condorcet criterion; it refers to a real correspondence between the rankings provided and the result produced. > "Condorcet simply discovers and applies this > preference. IRV, on the other hand, elicits enough > information to discover it exists, but may decide to ignore > it based purely on procedural grounds. There are no good > reasons for this, ever." > IRV meets Later-no-Harm and Later-no-Help and is immune > to Burial strategy, and these properties are incompatible > with the Condorcet criterion. > Some people think these "reasons" are > "good". I know some people claim that there are good reasons to use non-Condorcet methods. I claim that when it gets down to installing a candidate over a candidate who beat him, which all non-Condorcet methods do sometimes (or else they'd be Condorcet methods), those reasons aren't good enough. Suppose my preference is Andrea > Brad > Carter, and Brad > Carter is a majority preference, but Andrea > Brad and Andrea > Carter isn't. Under IRV, I am sometimes (but not always) forced to hold on to Andrea until I no longer have any chance of helping Brad beat Carter, even if my preferences are more like Andrea > Brad >>>>> Carter. This quality strikes me as perverse. Nevertheless, Condorcet's failure of LNH is connected to a serious weakness, vulnerability to burial. But this means that when my later preferences do "hurt" my favorite, things are as they should be because it means I didn't create an artificial cycle. > BTW, which of the many methods that meet the Condorcet > criterion is your favourite? > Chris Benham > You're really asking which completion method is my favorite, and I don't have any strong preferences. I believe an actual runoff for the Smith set would be the most appropriate: it would give voters a chance to reconsider with their attention focused on only the serious candidates, and make strategy harder to use. If, for example, the cycle existed because a large number of ballots were Republican > Green > Democrat, the Democrats will have an opportunity to use counter-strategy, or even make the apparent manipulation a campaign issue. It's not really reasonable to have a third or later vote, so some reasonable completion method will need to be used. ---- Election-Methods mailing list - see http://electorama.com/em for list info