Tell it to Bar-Kochba:

"J Street" founder Jeremy Ben-Ami: "The fallacy here [regarding the war in Gaza] is the argument that a military victory against an insurgent group actually is achievable."

Of course, there are a lot of much more recent (and often much less bloody) examples of military victories against "insurgent groups" than the Roman victory over Bar Kochba, including, tellingly, Operation Defensive Shield's crushing of the Second Intifada on the West Bank in 2002-03.

I continue to remain agnostic on the ultimate wisdom of the Gaza operation, given the information gap between me and those who planned it. It may turn out to be a brilliant, necessary, tactical and strategic endeavor, and it may turn out to be a fiasco motivated in its timing and scope primarily by domestic Israeli political considerations. But to claim, as Ben-Ami and others (e.g.) have, that military victory against insurgencies is inherently unachievable, reflects the equivalent of an a priori quasi-religious belief in the futility of military force.

UPDATE: BTW, and relatedly, one thing I've noticed about bloggers, including liberal Jewish bloggers, who are confident that Israel's military action in Gaza is a strategic blunder, is that they rarely if ever nevertheless express the hope Israel will win, and win convincingly. One might think that when the battle is between Israel on the one side, tacitly supported by the Palestinian Authority, Egypt, and Jordan, and Hamas on the other, supported by Iran and Hezbollah, one would at least hope for an Israeli victory, even if one is dubious about its prospects. But I get the feeling that for many, it's more important that Israel, and the world, learn a lesson about the "limits of military force" than that a violent, fanatical, backwards, illiberal, anti-Semitic terrorist organization be humbled defeated.

FURTHER UPDATE: Barry Rubin asks what you should think about Hamas, if you "love the Palestinians, are sympathetic to Arabs, and are indifferent to Israel."