Haven't seen THAT argument before

Jeff Jacoby, in the Boston Globe: If he were alive today, JFK would be a Republican.

Arguments. JFK:
1. cut taxes
2. opposed affirmative action
3. vicious anti-communist

These are all true, so far as it goes. JFK was notoriously a slow mover on civil rights and somewhat of a hawk (though the "missile gap" was mainly a political ploy, and he was the voice of reason in the Cuban missile crisis).
But Jacoby makes tremendous errors of scale. There is a difference, for example, between cutting top marginal rates from 91% to 70%, as JFK did, and claiming that raising top rates from 32% to 35% (approximately) is "socialism."

I don't see JFK in the latter camp.

Times change, and the politics of the possible changes with them. Is there any reason to think that JFK, were he alive in 2009, wouldn't hold substantially the same positions as his recently-deceased younger brother?

To top it off, Jacoby concludes by arguing that Eisenhower is closer to the modern-day GOP than JFK is to the modern Dems. Goldwater, anyone?

See also David Greenberg on why JFK was no supply-sider.