Yours truly have no problem with Krugman’s views on the use of math in this video in his recent tweet. I have said similar things myself for decades.

But there is a BUT here …

At other times Krugman — although admitting that economists have a tendency to use ”excessive math” and “equate hard math with quality” — has however vehemently defended the mathematization of economics:

I’ve seen quite a lot of what economics without math and models looks like — and it’s not good.

And when it comes to modeling philosophy, Krugman has more than once defended a ‘the model is the message’ position (my italics):

I don’t mean that setting up and working out microfounded models is a waste of time. On the contrary, trying to embed your ideas in a microfounded model can be a very useful exercise — not because the microfounded model is right, or even better than an ad hoc model, but because it forces you to think harder about your assumptions, and sometimes leads to clearer thinking. In fact, I’ve had that experience several times.

For years Krugman has in more than one article criticized mainstream economics for using too much (bad) mathematics and axiomatics in their model-building endeavours. But when it comes to defending his own position on various issues he usually himself ultimately falls back on the same kind of models. In his End This Depression Now — just to take one example — Krugman maintains that although he doesn’t buy “the assumptions about rationality and markets that are embodied in many modern theoretical models, my own included,” he still find them useful “as a way of thinking through some issues carefully.” When it comes to methodology and assumptions, Krugman obviously has a lot in common with the kind of model-building he otherwise — sometimes — criticizes.

My advice to Krugman: stick with Marshall and ‘burn the math’!