I’m impressed by Michael Gerson’s attempt to turn someone’s having been right about something into a liability.  He concedes the point that Obama has been right about Iraq in the past–it seems, according to Gerson (himself one of the chief rhetorical motivators for invading Iraq), that invading Iraq was a colossally bad idea.  (Good for him, good Christian that he is.  But there ought to be some penance involved in that admission–especially on account of the key role he played in making it a reality.  Maybe he ought not to seek the credulity of the reading public.  But I digress.)

Back to the argument.  Since Obama cites having been right about Iraq as a credential when he now argues about Iraq, he’s "living in the past."

The situation in Iraq, as Gen. Petraeus insists, is "fragile and
reversible." But the debate has moved far beyond a candidate’s initial
support for the war. This has led to an odd inversion of the
generational battle. Young Obama’s strongest arguments are focused "on
the failures of the past." The older man, by insisting on victory, is
more responsible and realistic about the future.

This has the air of a sophism about it.  Judgments about the future rely on the past in two ways.  (a) One who has a record of being right in the past will justifiably point that out as a credential; (b) what is going to happen can only be determined on the grounds of what has happened.  So naturally in order to decide resolve what to do in Iraq, one will have to focus on the failure of the past–failures, Obama would point out, John McCain’s keen political judgment is responsible for. 

So the question, "who is more responsible and realistic about the future" depends, of course, on the past.  For, "who has been more responsible and realistic [on this specific problem, by the way] in the past?" seems to be a rather reasonable way to resolve who will be more responsible in the future.

But what do I know.  I was right about Invading Iraq.