Yglesias and Drum do a little accidental debating here:

I'm glad that Senator Rob Portman of Ohio has reconsidered his view on gay marriage upon realization that his son is gay, but I also find this particular window into moderation--memorably dubbed Miss America conservatism by Mark Schmitt--to be the most annoying form.

...

Rob Portman doesn't have a son with a preexisting medical condition who's locked out of the health insurance market. Rob Portman doesn't have a son engaged in peasant agriculture whose livelihood is likely to be wiped out by climate change. Rob Portman doesn't have a son who'll be malnourished if SNAP benefits are cut. So Rob Portman doesn't care.

...

Obviously the answers to complicated public policy questions don't just directly fall out of the emotion of compassion. But what Portman is telling here is that on this one issue, his previous position was driven by a lack of compassion and empathy. Once he looked at the issue through his son's eyes, he realized he was wrong. Shouldn't that lead to some broader soul-searching?

Vs.

I admit that my first reaction to this was disgust: I'm tired of conservatives who suddenly decide that Medicaid should be more generous with stroke victims after they've had a stroke themselves, or who suddenly decide gay marriage is OK when someone in their family turns out to be gay. Is it too much to ask that they show a little empathy even for people and causes that don't directly affect their own lives?

But first reactions aren't always right. I do wish conservatives could demonstrate a little empathy even for people and causes that don't directly affect their own lives, but it's not as if this is an exclusively conservative thing. It's a human thing. Personal experience always touches us more deeply than facts and figures, and in the case of gay marriage we all knew this was how progress would be made...

We all knew this was how it would happen, slowly but steadily. We knew it. And now it's happened to Rob Portman. It's progress. It's human. And I should be less churlish about it.

I'm with Yglesias here. There's a limited number of issues that can turn out to directly affect a politician, so having empathy and/or the ability to apply the implications of policy positions to actual people ought to be one of the job requirements. I'll take progress any way i can get it, but intellectually, a guy that believes homosexuality is morally wrong even if his son is gay makes more sense to me than a guy who changes his opinion only when it affects him personally.