The Inexact Science of Economics – and Brexit

Some argue that economics is not a science because it is not able to prove  theories ‘beyond doubt’ the same way as the hard sciences can. Or put another way: most economic theories cannot be disproved in the same way that Popper thought scientific theories could be disproved.

Simon Wren-Lewis objects, defining economics as an inexact science, but science nevertheless. He concedes that in economics no single experiment or regression can kill a theory but points out that economists “[…] have accumulations of evidence that confirm the applicability of some theories and reject the applicability of others. Economists’ views about what models are applicable change as this evidence accumulates.”

I find the term inexact science very fitting and basically agree with Wren-Lewis’ remarks on the topic. But then he ruins it in the last paragraph of the post:

This is why economists views about the (negative – ed) long term impact of Brexit should be treated as knowledge rather than just an opinion. Here knowledge is shorthand for the accumulation of evidence consistent with plausible theory. Sometimes the theories are common sense, like making trade more difficult will reduce trade. Estimates of the size of trade reduction based on evidence are uncertain, but they are better than estimates based on wishful thinking. Empirical gravity equations consistently show that geography still matters a lot in determining how much is traded. Finally there is clear evidence that trade is positively associated with productivity growth. To say that all this has no more worth than some politicians opinion is ultimately to degrade evidence and the science which interprets it.

Not so fast. Economists indeed know that making trade with EU countries more difficult, which Brexit undoubtedly will, will have a negative effect on British incomes. However, the EU is not only a free trade area but also (and arguably more importantly) a political union, producing a large amount of legislation each year.

For example, banking regulation is basically completely defined at the EU level, with national discretion restricted to a couple of unimportant parameters and risk-weights.

That is, Brexit will also have an effect on the laws and regulations under which the UK economy is going to operate. Will this legislative effect of Brexit be positive or negative for British incomes? As I said before, nobody can know for sure.

However, EU legislation certainly has room for improvement (to put it politely) and, in general, smaller political entities tend to be governed better than larger ones. Hence, the legislative effect on British incomes may well be positive. Furthermore, the legislative effect of Brexit might not only be positive but also strong enough to more than offset the negative effect of making trade with EU countries more difficult.

In short, the net effect of Brexit on British incomes may well be positive.

The undue certainty with which many economists have made their predictions on the economic consequences of Brexit is based on ignoring its legislative effect. This effect is, of course, more difficult to measure and to predict than the effect of restrictions to free trade with EU countries. That doesn’t mean it’s not important.