Some years back, I managed to get this beat up basic math book from a friend. It had an interview in there from Kenneth Arrow that I liked. I think you’ll like this quote, too:
But you say, “Well, okay, since we can’t get perfection, let’s at least try to find a method that works well most of the time.” Then when you do have a problem, you don’t notice it as much. So my theorem is not a completely destructive or negative feature any more than the second law of thermodynamics means that people don’t work on improving the efficiency of engines. We’re told you’ll never get 100% efficient engines. That’s a fact — and a law. It doesn’t mean you wouldn’t like to go from 40% to 50%.
Here, Kenneth Arrow is referring to his Impossibility Theorem, which says that ordinal voting methods can’t fulfill some basic criteria that he thinks voting methods should be able to meet.
I tend to prefer cardinal methods (scoring based). But there are other theorems out there that also apply to cardinal methods. And so you get back to Arrow’s idea, which essentially is, let’s do as well as we can.
When the question is plurality versus instant runoff voting (IRV), I’m going to be on your team and pick IRV. Plurality is so all-around awful and sensitive to vote splitting that the marginal improvement with IRV is likely worth its relatively complex algorithm, special required software, and sometimes unpredictable results.
Plurality is a low bar though. On the other hand, when you compare IRV to something that isn’t plurality, like approval voting, then we’re on different ground. Approval voting is simple. It lets you pick all the candidates you want, most votes wins. Like any voting method, of course, it has its imperfections. But it’s so easy, performs well, and is one of the rare voting methods that always lets voters pick their honest favorite, no matter what. Combine that ability to support your favorite with how easy the results are to read, and you have a recipe for political competition — which is what makes a democracy healthy.
In terms of bang for your buck results, my money is with approval voting. When you start talking about primaries, we can simplify things like most countries do and let the parties pick their candidates and let independents run on their own. If we’re to insist on primaries, then we should at least make them open, use approval voting, and let the top four go onto the general election.
Making the primary open makes your electorate sample closer to that of the general population. Using approval voting gets more of a moderate, consensus winner, given the electorate. And taking four to the general election encourages some competition, makes it harder for financial interests to have a sure bet with candidates, and gives third parties more of an opening to join the larger stage.