Jon Chait has already explained why attacks are more damaging to a candidate when they come from someone in his own party. But beyond that, there seems to be a logical flaw in the argument of Clinton apologists (e.g. Paul Krugman) who claim that the Clinton campaign's attacks are in fact acceptable politics. Here is Krugman in his Friday column:

According to many Obama supporters, it's all Hillary's fault. If she hadn't launched all those vile, negative attacks on their hero — if she had just gone away — his aura would be intact, and his mission of unifying America still on track.

But how negative has the Clinton campaign been, really? Yes, it ran an ad that included Osama bin Laden in a montage of crisis images that also included the Great Depression and Hurricane Katrina. To listen to some pundits, you'd think that ad was practically the same as the famous G.O.P. ad accusing Max Cleland of being weak on national security.

It wasn't. The attacks from the Clinton campaign have been badminton compared with the hardball Republicans will play this fall. If the relatively mild rough and tumble of the Democratic fight has been enough to knock Mr. Obama off his pedestal, what hope did he ever have of staying on it through the general election?

It's worth noting how Krugman sloppily dances from accusation to accusation; regardless, he seems to half-concede that using Osama Bin Laden in an ad is slightly dirty but nevertheless acceptable because the Republicans will do worse. And since the GOP is pure evil, if Clinton attacks Obama in the hope of toughening him up for November, well, that's alright. 

Krugman is one of those liberals who over the past six years has been disgusted with more than the Bush administration's policies; he frequently mentions "dirty" Republican attack ads and what he considers the unscrupulous way in which The Party of Lincoln goes about winning elections (a cursory search turned up six references to the Cleland ad in his columns). If I read Krugman correctly, then, he has argued (before Friday) that the ends do not justify the means (or, to put it another way, Republicans may be within their rights to try and win elections, but the task must be undertaken with at least minimal ethical standards).

But wait: Now Krugman is saying any sort of tactic is fine as long as it leads to Republican defeat (of course I am giving Krugman the benefit of the doubt on his ridiculous argument that these attacks are actually helping Obama). But by this standard, the Republicans are free to run campaigns however they see fit, too.  

Finally, this passage from Christopher Hitchens' old Atlantic review of Sidney Blumenthal's memoirs is worth recalling:

But just wait for the good people's party to be caught doing something shady or vile; at once you will be told that it's no worse than what the bad people's party would do or has done. Immediately, in other words, the apologist will admit that the game is up, and that he is judging his own team by a standard (of ghastliness in others) that he himself helped to set. "They all do it" means, in this circle, "We all do it." But the apologist won't concede this consciously or honestly. Faced with the task of explaining the Clinton pardons, including one to Marc Rich, Sidney Blumenthal, a former senior Clinton adviser, immediately responds, in The Clinton Wars, that Richard Nixon pardoned Jimmy Hoffa; and as for the $190,000 in gifts accumulated by the Clintons, it was "roughly the same amount as the preceding Bushes had accepted." Since he elsewhere accuses the Republican Party of being essentially lawless and segregationist, he might admit that he's setting himself a low standard. But he doesn't get the joke.

Isaac Chotiner