SCOTT SIMON, HOST:

This is WEEKEND EDITION from NPR News. I'm Scott Simon. The agreement to restrict Iran's nuclear program while easing economic sanctions took almost two years to negotiate and will set off an intense and historic debate in the U.S. Congress. Public figures began to denounce or praise it instantly. Stephen Carter, the Yale University professor of law, novelist and author of many nonfiction books, including "The Violence Of Peace: America's Wars In The Age Of Obama," has actually read the fine print. He joins us now from Yale. Thanks so much for being back with us, Stephen.

STEPHEN CARTER: It's a great pleasure. Thank you for having me on, Scott.

SIMON: In pursuing this deal, has the administration elevated concern about Iran's nuclear capabilities over concerns about its human rights record, its profile in the world stage, its support of terrorist groups?

CARTER: Well, I would put it another way. It's important to remember that the diplomacy under which this agreement was reached began as simply a matter of dealing with the Iran nuclear arms potential. That was what was seen as the great destabilizing force in the Middle East, and that this deal is mainly aimed at taking away. The question of whether yielding a bit on those other issues is good or bad depends on how big you think the threat was. It depends on what you think of the threat of Iran with a bomb and what you think of the chances they really would have been able to create one. If the deal works the way the administration thinks it will, if a lot of these measures stay in place for 10 or 15 and, in some cases, 25 years, and if the regime of inspections works well, then the trade-offs may well be worth it. But if that doesn't work, if Iran is able to cheat and at the same time has $100 billion or $150 billion of money from sanctions relief and more later on, that it ends up using to spread terror and stability, then it will look like a very bad deal. But as a scholar, I have to say that we can't really tell until somewhere down the road.

SIMON: Oh, my gosh, time will tell?

CARTER: (Laughter) Well, you know, it's interesting. You mentioned, Scott, that a lot of people had immediate responses to the deal, and it's hard to have an immediate response. It's a very, very complex deal. There are a lot of moving parts. In a way, that's one of the reasons to be worried about it. With a deal this complex, things are bound to go wrong. I saw in The New Yorker the other day, someone referred to it as a Rubik's Cube deal. I think it's more of a Rube Goldberg deal. There are a lot of things - a lot of little levers and pulleys - that all have to work together exactly right. The chances that something will go wrong are huge with a deal of this complexity. The question is whether something does go wrong, that whatever goes wrong will be small enough that the deal as a whole will still be a good one.

SIMON: The whole fascination of a Rube Goldberg machine is seeing things almost go wrong. Is the hope of this deal that if something goes wrong, it's a small something that doesn't jeopardize the overall deal?

CARTER: Well, let me put it this way. Game theorists who study arms control have long made the point that even if you have a deal where you are sure the other side will cheat, that doesn't mean it's a bad deal. The question is whether your gains from the agreement are still greater than the costs that you would have from not having agreement. You can have gains from an imperfect agreement. So if this is a Rube Goldberg machine that works, it may mean that although everything will not go exactly right, overall, looking back a decade from now, we'll be happier than not the deal existed. And that's what the administration is betting on. That's what President Obama is betting his legacy on. The problem of the Rube Goldberg machine, of course, is that with all of that complexity, if one of those little pulleys actually comes loose, the whole machine can start to fly apart.

SIMON: Stephen Carter, Yale University law professor, author and novelist. Thanks so much for being back with us.

CARTER: It's been my pleasure. Thank you again. Transcript provided by NPR, Copyright NPR.