[zoul]

As I understand it, the recent economic turmoils in various parts of the world seem to have shed a new light on the mathematical modelling of real economies. While the models might be a good discussion tool, forcing the parties to explicitly state various assumptions and ideas, they are essentially useless for predicting a real world economy.

And what’s worse, they seem like something dependable. Isn’t it very hard to judge how much a model has to do with reality? A discussion about a model might be a perfectly scientific, constructive and relevant discussion about a theoretical world that has almost nothing to do with the real one.

[Radim]

No, it might not. Not unless you use the word "scientific" in some creative way.

The "real world" is a necessary component for the scientific method. By comparing model predictions to real-world experiments, it allows refuting and refining models and theories. How else would you evaluate theories, to separate the chaff from the grain?

The feedback from observation is absolutely vital.

[zoul]

Please don’t generalize my arguments to scientific method as such, I am just talking about economy. A real-world economy is a wildly nonlinear system, a bit like the weather. And there’s always something important you may fail to take into account, like the role of the private financial sector in the recent economic crisis. You may argue that we are now wiser and our models better, but the plain fact is that the degree of correspondence between our models and the real economic world is very poor. When you tweak a model for such a complex system, how do you scientifically know it’s better for predicting the future behaviour? It’s madness to think that you could reasonably model what would happen after introducing a minimal income.

[Radim]

I agree with you, but that changes nothing.

You're basically saying that economy is not science, in the sense above. Which I agree with. It is madness.

This doesn't mean that things outside science cannot be useful -- just that it's not science.