Yesterday I had lunch with an old friend who is a top monetary economist. We were discussing a conference on the state of macroeconomics that I attended recently. The conference seemed to me to reveal quite a deep division between those macroeconomists who thought their pre-crisis New Keynesian DSGE models were basically fine, although obviously in need of having a financial sector added to them, and other economists taking a wide range of approaches but pretty sure the pre-crisis mainstream approach is defunct. I’m in the latter category, with the caveat that it’s nearly 25 years since I’ve done any proper macroeconomics.

Alas, my dear friend is in the amended status quo camp. He said the tools a monetary economist needs can be found in the Michael Woodford tome [amazon_link id=”0691010498″ target=”_blank” ]Interest and Prices: Foundations of a Theory of Monetary Policy[/amazon_link]. His argument went like this. Any macro model makes simplifying assumptions. We macroeconomists could have assumed that prices and wages are perfectly flexible, which would make the models easier, but we didn’t. That was a correct call. We did make the simplifying assumption that the financial sector was a veil and we could ignore the incentives on bankers’ behaviour, and that was a misjudgment. But economists understand incentives, it’s straightforward to fix, and we’re putting the financial sector into the models now.

[amazon_image id=”0691010498″ link=”true” target=”_blank” size=”medium” ]Interest and Prices: Foundations of a Theory of Monetary Policy[/amazon_image]

This argument is on the face of it perfectly reasonable, but it reminds me of a conversation I had with another tleading economist in the mid-1990s, when I was working as a journalist reporting on technology and becoming enthused about the likely implications of the internet and World Wide Web for the economy. This economist argued that all the internet did was reduce transactions costs, and economists understand how to model transactions costs, so the new technologies would turn out not to be very interesting analytically. This was also true in a small way, and false in a much bigger way.

The moral is that the judgments reflected in simplifying assumptions are not a small technical matter. Transactions costs are not a side-show in economic analysis, they are the main attraction, driving the fundamental structures and institutions of the economy. So it is with the assumptions behind conventional macro models, which encapsulate a world-view about the nature of economic and political institutions  – the failure of pre-crisis DSGE models is not a question of small and easily corrected misjudgements but rather missing the main point.