Matt Yglesias: They’ll do anything to help the Palestinian cause unless it involves spending money, risking the stability of their own regimes, or deploying their military assets. Now we’re supposed to believe that, suddenly, the Mullahs are willing to guarantee their own destruction in order to turn the holy city of Jerusalem into a radioactive wasteland.
Matt McIntosh: One of the largest sources of error in reasoning about other people’s behaviour is paying more attention to what they say than to what they do. It’s the kind of error that causes people to continue to think of Republicans as being the party of small government, or that the unions stick up for “the workers” rather than just the unions, or that Middle Eastern authoritarian regimes actually give a damn about Israel as anything other than a useful political prop. (It’s often joked that if Israel didn’t exist, they’d have to invent it.)
It’s a fallacy on par with the fundamental attribution error, and so ubiquitous as to deserve its own name – perhaps “the rationalistic fallacy”
This is certainly true. However there is a similar and similarly widespread error in reasoning which is to downplay or ignore outright evidence which points to an unsettling conclusion. This would be the kind of error that causes people to dismiss out of hand a plainly spoken intent in favour of some imagined unspoken "real intent" more congenial to the worldview one wishes to maintain.
There is also the type of "fundamental attribution error" I previously described as "homomorphism", which is to project one's own reasoning and rationale to another. Perhaps this might be called the "rationalistic" fallacy. It certain doesn't seem to make any sense for Iran to nuke Israel and/or provoke an attack from the USA. But plenty of things end up happening which didn't seem to make any sense.
For instance, Saddam's behaviour in the run-up to the Iraq war didn't seem to make any sense from the point of view of the preservation of his regime. Turns out he didn't have any wmd worth a damn. This could have been made amply clear by full co-operation with inspectors which would probably have fatally weakened the case for invasion. Instead, it seems that it was more important to maintain his self-image as a latter day Saladin than it was to save his own skin.
Prior to Sep 2001, it "didn't make any sense" to believe that terrorists would commandeer a plane to use as a missile - so much so that I (admittedly dimly) recall a report by a Guardian/Observer/Channel 4 journalist (Possibly Jon Ronson?) mocking the hubristic plans of Abu Hamza and his acolytes who had discussed this very possibility in a semi-public meeting attended by the hack in question.
The problem here, I'd suggest is the slide from estimating a low probability of a certain course of events - Matt (both of them!) may well be right that such a self-defeating turn by Iran following through on its sabre-rattling is unlikely - to the certainty that that course of events won't take place. The corrollary to the Matts' argument is that one shouldn't worry about Iran becoming a nuclear power. I don't think this is a safe conclusion at all. For example, let's say we could have flicked a switch a few decades ago and prevented Pakistan from going nuclear (hell, throw in India while you're at it) I think we would have. The world is almost certainly a more dangerous place with Islamic-terrorist-supporting generals a heartbeat (or a neatly timed assasination) away from the red button.
This is not to say that there is a cast-iron case for action against Iran. Rather it's to point out that this question - what Iran's "real intent" is likely to be in the event that they acquire nuclear weaponry - is the wrong question. For one, bellicose threats, however hollow, can tend to become self-fulfilling prophecies, particularly when delivered by a populist demagogue. The pertinent question is whether it is possible to stop Iran from going nuclear in the first place without either introducing perverse incentives for other "rogue" states (the danger in "soft" power"/bribery) or without leading to a conflagration worse than the threat represented by a nuclear Iran. I don't think this is a settled question but I'm certainly not going to seek consolation in the comforting notion that a nuclear Iran is ok because, when they rattle their sabres, they don't really mean it.