Deciding whether or not to approve the deal struck by the U.S., Britain, France, China, Russia and Germany with Iran regarding its nuclear capacity clearly calls for applying the approach of the comedian Henny Youngman, whose answer to the question “How’s your wife?” was “Compared to what?”

There is a tendency for people to judge a particular response to an undesirable situation against what they envision as the ideal outcome. But doing so ignores a fundamental fact: Possible solutions to difficult problems are very much constrained by the real-world facts that created the problem in the first place. Two such unpleasant but unavoidable facts not only make it very difficult to achieve the very desirable goal of insuring a non-nuclear armed Iran, but also explain why for all of his eagerness to do so, President George Bush made no progress on this front. The constraints were firmly in place when President Obama took office.

The first of these is well-recognized: the very existence of an Iran governed by religious fanatics who are deeply imbued with hostility to Israel, the democracies of the West and Muslims who interpret their faith differently, and who also are convinced, with good reason, that the U.S. and our allies would very much like to see them replaced by rulers who are much less belligerent toward those they regard as enemies.

But there is a second limiting factor on America’s ability to prevent Iran’s current rulers from acquiring nuclear weapons that is much less acknowledged by those calling for rejection of the recent agreement, and to which I referred in my opening sentence: The only way our country could have even tried to achieve this unilaterally is by a major military assault.

I am proud to have been one of the early sponsors of the economic sanctions legislation that has been the critical factor in forcing the Iranians to make the significant concessions the agreement embodies. But I knew when we began this effort that they would only be effective if we were joined by most of the rest of the world in imposing them.

Acting with the president’s full support, Secretary of State John Kerry has done a masterful job of holding this coalition together. It was far from inevitable that Russia and China, intent as each of them is on reducing America’s influence in the world, would continue their participation in the multinational effort necessary to inflict enough economic pain on Iran to get us to this point. Insisting on further Iranian concessions – for example on issues not related to the nuclear weapons issue – would have fractured the coalition, resulting not only in no agreement, but also with Iran having broken out of the economic barricade.

IGNORING TWO REALITIES

The argument that we could have achieved a deal in which Iran foreswore even a civilian nuclear capacity ignores these two realities. There is a deep inconsistency in the view that Iran is so implacably hostile to us – and so determined to violate any agreement it makes – that we should not have signed off on this agreement but could somehow have both persuaded them to concede even more and trusted them to live up to this hypothetical tougher deal. And that hope is especially a fantasy given the fact, well-known to the Iranians, that we would have been forced to try to accomplish this without the broad coalition that got us this far.

There is an explanation of the fact that many sophisticated critics, who understand these constraints, continue to insist that a better deal was possible. Most of them in fact are opposed to any agreement but understand that clearly stating this preference lacks the political support they need to defeat it.

But the conclusion that there is no remotely achievable outcome that would get their support is implicit in the views of Israeli Prime Minister Benjamin Netanyahu and leading Republicans in America.

They note that given Iran’s continuing hostility to Israel’s existence, a deal that ends sanctions strengthens Iran economically and politically. But that is an argument for no deal short of one that transforms Iran’s basic political structure, an outcome I would be very happy to see, but one that neither they nor I believe is remotely possible in the foreseeable future.

Of course if the deal does nothing significant to limit Iran’s nuclear weapons capacity it should be rejected even if, as is clearly the case, it was the best that could be gotten. But Youngman’s measuring stick gives a different answer.

Iran is now one of the few nations with a nuclear weapons potential that has renounced the effort. You do not have to be a fan of the Iranians to recognize that they do care about their image in the world, and know they will pay a heavy price in places where they seek approval if they blatantly break their word. Moreover, they have accepted a set of strict limitations on their nuclear effort and an intrusive inspection regime that go well beyond what their regional opponents – e.g. Israel and Saudi Arabia – would tolerate. And if they violate their agreements, our ability to re-impose broadly supported tough sanctions will far exceed what we could have done if we rejected the current arrangement.

Compared with the no-deal result, with Iran free to pursue nuclear weapons constrained only by unilateral sanctions from America and a few of our allies, what Obama and Kerry have done deserves support.

Barney Frank is a retired congressman and the author of landmark legislation. He divides his time between Maine and Massachusetts.

Twitter: BarneyFrank