Digby had an excellent post yesterday on whether Obama should choose, as his running-mate, a Republican in order to play to the middle in November, or whether it would be strategically preferable to run to the left with an all-out progressive ticket.

Naturally my preference, like hers, is for the latter. But, again like her, I’m not completely convinced. Behind my hesitation lies a thought from the obscure 18th-century German philosopher, Georg Bernhard Bilfinger (1693-1750). Kant, in his early philosophy, was much taken with something he called ‘Bilfinger’s Rule’. Kant expressed the Rule thus:

if men of good sense, who either do not deserve the suspicion of ulterior motives at all, or who deserve it equally, maintain diametrically opposed opinions, then it accords with the logic of probability to focus one’s attention especially on a certain intermediate claim that agrees to an extent with both parties (quoted in Martin Schönfeld, The Philosophy of the Young Kant: The Precritical Project, Oxford University Press, 2000, p. 59).

I think many people instinctively gravitate towards a political version of this. ‘Extremists’ all equally deserve the suspicion of ulterior motives; hence, political wisdom is always found in the middle. (Perhaps the political version should be called ‘Broder’s Rule’.)

One might think that the political version of Bilfinger’s Rule (I dislike Broder too much, and like the name ‘Bilfinger’ too much, to follow my own suggestion for renaming) could be justified as follows. A certain course is the position of wisdom. People will naturally, owing to various ulterior motives, be pulled to various sides of it. One can therefore determine what the best course of action is by looking at the extremes and finding the middle between them. (Call this, for reasons that will be clear to philosophers, the extensional version of Bilfinger’s Rule.) This is obviously a bad rule. What the ‘extremes’ are varies greatly over time and with geographical and cultural circumstances. The ‘middle’ in Europe comes out far to the Left of the ‘middle’ in the USA. So why think that, in any given situation, the extremes will be such that the best course just happens to be half-way between them?

But another interpretation of the Rule, (call it the intensional version) has it that, whatever the ‘extremes’ are, the best course of action is whatever lies in the middle of them. This might be justified by the thought that, however crazy you think the other side is, they are still (roughly) half the people, and you have to get along with them. Give them some of whatever it is they want, and they will give you some of whatever it is you want, and you’ll all get along as best you can. Try and get everything you want (even if, objectively, that’s the best course) and they’ll fight you all the way. Compromise is best not because it will settle on what is the best possible course, as the extensional version of the rule has it, but simply because it is a compromise. This is a lot more plausible than the extensional version of the Rule. After all, one does have to live with those whom one opposes politically. But it is grating in the extreme. If you have the best course of action, why should you have to give any of it up just to get along with some bozos on the other side?

Progressives will certainly not think that by choosing a Republican VP candidate (or a centrist Democrat for that matter), Obama’s platform will objectively improve. Quite the opposite. The only justification for doing it is that it will be a compromise that might help us to get some of what we want. But it will be grating in the extreme. As I said, like Digby, I don’t know whether it will be worth it. Will it be necessary? Can we win without compromise? And will it be sufficient? Or will we lose more by dampening the enthusiastic support of those on whom compromise will grate the most than we will gain by appealing to centrists and moderate Republicans?