Yesterday I appeared on a panel at J Street, where I debated Matthew Yglesias on what it means to be pro-Israel, as well as J Street's role in this debate. My main argument was that the Jewish community needs a group like J Street to keep the most extreme elements from defining "pro-Israel" too restrictively, to provide a counterweight against the natural inclination of any ethnic community toward tribalism, and to provide political space for the territorial compromises needed to create a two-state solution.

The problem, though, was that J Street had loosened the definition of "pro-Israel" to the point where it had virtually no meaning. As a result, the group has attracted the support of a lot of people who do not think of themselves as pro-Israel at all, some of whom oppose Israel's continued existence as a Jewish state. My bottom line was that J Street could be a group that represents a significant chunk of the American Jewish population, or it could be a group that represented people with Walt/Mearhseimer-esque views on Israel, but it couldn't be both and would have to choose.

What's interesting to me is that this tension has been apparent to numerous observers of the conference, including people who approach the problem from the opposite ideological side. Left-wing anti-Zionist Phillip Weiss noted that the J Street crowd was much more left-wing than the group's leadership. Max Blumenthal protested J Street President Jeremy Ben-Ami's moderate interview with Jeffrey Goldberg. And Yglesias, who began the panel by disputing my thesis, wound up changing his mind and agreeing with it.

My main thought coming out of the J Street conference is that J Street has a huge problem on its hands. It's trying to win political influence and compete with AIPAC to speak for the center of American Jewry on the Middle East. Meanwhile, its most enthusiastic supporters have beliefs that are totally incompatible with this goal. J Street has played a delicate political game, sending different messages to different constituencies, but something is going to have to give.

The video of my debate is here:

Debate: Jon Chait & Matt Yglesias square off on what it means to be pro-Israel from Isaac Luria on Vimeo.