The problem is that the Overton window does not move back in a direction of less intervention through nuanced critiques of the most extreme position. Believe me, I wish it did. Instead, it needs to move using the same kind of stridency and demagoguery that pushed it in its original direction. So while I personally wouldn’t agree with categorically ruling out the use of force against Iran no matter what, opponents of preventative war are going to have to make some politically risky declarations if they expect the consensus to start to move in their direction.
Scoblete may be right, but as a matter of intra-Republican politics that might not work. Ron Paul discovered that there was a ceiling for his support in the Republican primaries because he took a radical dissenting position against most consensus views on foreign policy. His campaigns had some success in dragging the intra-Republican debate back in the direction of sanity, but could only take it so far. Whatever else one wants to say about it, Rand Paul’s speech was an attempt to meet most Republicans where they are at the moment in the hopes of moving them in the direction of restraint. There is a significant Republican constituency for a more restrained U.S. foreign policy that is less involved in the affairs of other countries*, but many of them aren’t represented by non-interventionists or hard-liners. In theory, these are the conservatives and libertarians that Sen. Paul was trying to reach on Wednesday. It remains to be seen how many of them were listening. It would be ideal if most Republicans could be persuaded that preventive war is wrong and illegal (which it is), but if they can be persuaded that preventive war against Iran is extremely unwise and imprudent that could be good enough.
* 44% of Republicans in the linked Rasmussen survey agreed that the U.S. is “too involved” in the Middle East.