Here’s a book reviewer I quite like, Scott McLemee, reviewing a writer I quite like, Lou Masur (who is also an editor I quite like). When a reviewer I like takes on a writer I like, it’s a bit like Batman v. Superman, or Stanford v. Cornell; I hate to see either side scoring too many points. Putting my sensitivities aside: both the reviewing and the reviewed texts meditate on this picture.

The history encapsulated in that photo may well be the reason Obama won’t win the primary in Pennsylvania. It’s probably also the reason for this:

Overall, 20% of white Democratic voters say they would vote for McCain if Obama is the Democratic nominee. That is twice the percentage of white Democrats who say they would support McCain in a Clinton-McCain matchup. Older Democrats (ages 65 and older), lower-income and less educated Democrats also would support McCain at higher levels if Obama rather than Clinton is the party’s nominee.

Which doesn’t, in that poll or others, mean Obama would lose—that poll shows him winning (and take all such polls with grains of salt; many things could happen between now and November). But it does suggest he would win with a different mix of votes than Clinton. In choosing a nominee, primary voters and convention delegates are choosing between different historical and future versions of the Democratic party, in which different mixes of people identify as Democrats, going forward.

And as with all Batman v. Superman matchups, the question is inevitably, which one is more powerful? Why?