David Andolfatto and Mark Thoma have posts defending macro theory from (some of) the people who say it failed us in the crisis. Both are good posts, and you should read both.
Anyway, here's a quick (and probably incomplete) taxonomy of criticisms people make about macro with regards to the crisis:
1. "Macro models failed to predict the crisis, therefore DSGE sucks."
This is the criticism that Andolfatto and Thoma reject. I basically agree. There are no other models out there that did forecast the crisis. Nor are expert predictions any better.
Personally I think DSGE techniques haven't reaped dramatic benefits (yet). But what other alternative is better? When I ask angry "heterodox" people "what better alternative models are there?", they usually either mention some models but fail to provide links and then quickly change the subject, or they link me to reports that are basically just chartblogging. Yeah, sure, if you put out hand-wavey reports saying "capitalism sux, there's gonna be a crash!" every year or two, you're eventually going to be able to say "see, I told you so". But that's no replacement for real modeling.
2. "Macroeconomists were too confident before the crisis, and that gave policymakers false confidence."
It is pretty obvious to anyone who has ever interacted with macroeconomists that most of them take their models way too seriously (this is even more true of the "heterodox", to the degree that they even have models). It's a common disease of academics in general - you have to spend so much effort pushing your theories that overconfidence is selected for.
Did this confidence leak over into the policymaking sphere? I don't have evidence here, but I doubt it. Most of the Fed people are a LOT less confident than academics. And they were being advised by a lot more than just the academic crowd - they had a big stable of chartbloggers, hand-wavers, etc. to draw upon. Plus they themselves had Old Keynesian models in their bag of tricks. As for politicians, it's not clear they even know that academic macroeconomics exists.
If the Fed people were overconfident in 2005-6, I suspect it was mostly due to natural cognitive biases - "Everything seems like it's been going OK for a couple decades, I guess we're doing something right" - rather than the overconfidence of the academics they interacted with.
But I could be wrong.
3. "Macroeconomists weren't focusing on finance enough before the crisis."
Thoma says that this is a valid criticism, and I agree. There are a bazillion models out there. But just having models out there isn't enough; if you're going to give policymakers real advice, you're going to have to choose which model - or which basket of models - to base your advice on. Macroeconomists weren't very worried about finance before the crisis - you didn't see a lot of people waving copies of Geanakoplos (2003) and saying we could be courting disaster.
Belief in the Great Moderation, and in the Fed's ability to stabilize the economy, was too strong. The central problem of depression prevention had not, in fact, been solved. But an awful lot of top macroeconomists - not just Lucas, but the New Keynesians too - thought it had. Their favorite models didn't have any finance in them, with the possible lone exception of the Bernanke-Gertler "financial accelerator" models.
That was a big mistake, especially since the Great Depression and crises in other countries (e.g. Japan) should have suggested that financial crashes were a big deal. To their credit, though, mainstream macroeconomists have been hastening to correct the mistake. Certainly they're going to pay more attention to finance for at least a few more decades.
4. "Macroeconomists don't do enough to kill their models off."
This is something I hear surprisingly few people say, given that I think it's the best of the criticisms out there. If you let a million flowers bloom but don't cut any of the flowers, you get a big warehouse full of flowers. OK, so that metaphor went nowhere, but you get the point. Macroeconomists, when they get defensive, tend to say something along the lines of "We got models for everythin'!" But is that a good thing??
I feel like if you have models for everything, you don't actually have any models at all. Without a way of choosing between models, your near-infinite stable of models turns into one big giant mega-model that can give anyone any results he wants. Worried about a financial crisis? Pull out a model that tells you a financial crisis could be looming. Worried about inflation? Pull out a model where inflation is a big danger. And so on.
Now, technically, you could choose between models based on the plausibility of the assumptions. But three things make this impossible in practice. First, the need for tractability means that the assumptions in almost any modern macro model will be utterly implausible to anyone who has not spent decades in a monastery high in the Himalayas training himself in the art of self-deception. Second, the assumptions are so stylized that it takes a huge amount of talent just to figure out what they are - in fact, we're starting to see the emergence of top macro people, like Matt Rognlie, who specialize in figuring out what the heck models are actually saying. And third, with a near-infinite catalog of models to comb through, there's just no way to compare any significant number of them all at once.
If you ever want macro models to actually be useful, it's not enough to just wave your hands and say "all models are wrong". It's not enough to treat models as ways to "organize our thinking". You've got to have a way to take them to data and decide if you should keep them around, send them back to the shop for alterations, or burn them in a fire.
5. "The crisis exposed the fact that macroeconomics doesn't work."
Well, sure. But it also showed that we need to keep trying to make it work. And macroeconomists, as a whole, don't absorb a significant fraction of our GDP, so I'm not incredibly worried.
Bumped from the comments, by an anonymous commenter:
[D]on't focus on macro *theory*. It's macro empirics I'd worry about. theory ahead of measurement etc. The difference post crisis is you see greater prominence of macro papers using micro data (e.g. mian sufi or autor/dorn/hanson/acemoglu).Great point.