Friday, August 6, 2010

Cosmology seems to make macroeconomics look decisive!

So I was watching the History channel last night, and they were showing an episode of The Universe called "Beyond the Big Bang", which covered cosmology, the Big Bang, and the formation of the universe immediately after the big bang. Neil deGrasse Tyson had a very interesting thing to say about cosmology:

"There were more theories running around than data"

Wow - that sounds familiar! It certainly doesn't seem to lead Tyson to call cosmology "fake science", as Russ Roberts likes to call macroeconomics.

Wikipedia confirms - check out the number of cosmological theories. You can even scroll down to the twentieth century, and it still puts macroeconomics to shame (Brad DeLong recently identified seven basic macroeconomic theories, compared to my count of twenty cosmological theories in the twentieth century alone).

I think another important point is that we fight over these macroeconomic theories, but ultimately that's kind of a weird thing to do. There's no good reason why most of them can't be integrated. Arnold Kling puts forward a mixed Minsky-Austrian story. I think Keynes, Minsky, and the Austrians all make sense and I'm perfectly comfortable with major tenets of monetary disequilibrium theory, and of course I believe real shocks can matter which means I don't think there's anything especially wrong with Real Business Cycle Theory. The problems come in when people point to a specific theory and say "this, and only this, is how macroeconomic fluctuations happen". Every recession is different, and presumably they're going to have a mix of causes. Macroeconomists have done a pretty decent job outlining these causes. What we need more of is understanding how these theories integrate together and what factors are important for what specific episodes. What we need less of is this attitude that there is one answer.

Are the twenty cosmologies as easily integrated and traded off? Well, they're explaining a single event and many of them contradict each other on the very nature of the universe, so probably not - but I'm sure to some extent they do.

I'm not trying to ridicule cosmology - as Tyson says, it's a matter of the data that's available - that's a limiting factor in science. But challenges don't make something non-scientific! Science is all about the method of gathering and testing knowledge.

Anyway, I just thought this was interesting. Phsyics is usually held up by the critics as some sort of gold standard. My response is "well, economics is really more like biology", but the fact is physics is struggling or has struggled with the same things that certain sub-disciplines of economics struggles with. That's life - science is hard.


  1. Most of the 20th century models have been rejected.

  2. Right, but it's hardly the narrative told by people who are skeptical that social sciences are sciences.

    The idea that we could have so many theories, that we can do scientific work with inconclusive data, etc. are all points used to diminish the social sciences.

    This isn't to diminish phsyics, obviously. It's to echo the point that sometimes "there are more theories than there are data", and you have to figure out how to work with that.

  3. Well, from my perspective the "social sciences" are even weaker in this arena than the natural sciences are.


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