Brexit: a worthless experiment

In an attempt to defend the indefensible, Janan Ganesh invites us to regard a ���hard Brexit���* as an experiment.

Sometimes history throws up ideas that are better tested than forever stymied���ideas, unless they are plainly malign or ruinous, have to be held accountable in the end by real-world application. There is only so much mileage in the statecraft of frustrating them.

A ���soft Brexit��� he says would allow Leavers to claim that any ill-effects are due to ���betrayal���, to not implementing Brexit properly. A ���hard Brexit��� would at least permit a proper ���falsification of their project���. And, he adds, if things work out badly we can rejoin the EU.

I���m unconvinced.

This experiment risks imposing real costs on real people ��� lower wages and unemployment. And as Neil Kinnock famously said, ���you can���t play politics with people���s lives���.

This objection, however, won���t work: it only applies to the left.

Instead, I���ve other objections to Janan���s piece.

One is that Brexit is not a scientific hypothesis to be discarded when it is falsified. Instead, Leavers have invested their ego in the idea; I question Janan���s claim that many are ���open to falsification."** This means that if a hard Brexit is followed by economic troubles, they���ll invent immunizing strategies to deny this.

And it���ll be easy to find such strategies. One reason for this is that a ���hard Brexit��� will not be a genuine experiment. In a true experiment, we can compare a treatment group to a control and so discover the effects of the treatment. But after a ���hard Brexit��� we���ll never see the control. We���ll not see the counterfactual, what would have happened if we���d stayed in the EU.

This matters. The case for remain is not that Brexit will lead to catastrophe but that it will cause slower long-term growth; real GDP will grow by a bit less than 2% per year rather than a bit more. If this happens, Leavers will be able to claim that Brexit wasn���t so bad. But this would be entirely consistent with the Remainers being correct.

Also, the Duhem-Quine problem ��� that we often can���t test hypotheses in isolation -  is especially severe in this case. Let���s say Brexit leads to slower growth in trade and productivity as Remainers claim. Leavers will find it easy to show other reasons for this. Exporters are ���fat and lazy���; investment has been low; secular stagnation means there���s little innovation. And so on.

And the thing is, these claims will have some truth. There are always many plausible explanations for poor economic performance.

You needn���t look far for an example of what I���m saying. On Radio 4���s Today programme this morning Gerard Lyons ��� one of the more sensible Leavers ��� claimed that a weaker pound was ���inevitable��� because of the UK���s big current account deficit (2���14��� in). That���s a way of denying an effect of Brexit.

I very much doubt, therefore, that a ���hard Brexit��� is a worthwhile experiment. Even if the Remainers are correct abut its effects, most Leavers won���t admit they were wrong.  

I suspect instead that Janan is giving us another example of the fact that there is no government policy so bad that it will entirely lack supporters; the corridors of power lend gravitas to even the daftest ideas. As Adam Smith said, ���We frequently see the respectful attentions of the world more strongly directed towards the rich and the great, than towards the wise and the virtuous.���

* I'm putting scare quotes around "hard Brexit" because I take Owen's point that the phrase serves framing rather than purely descriptive purposes.

** Yes, some are. But the better Brexiters such as Daniel Hannan and Andrew Lilico are already having their doubts; I'm thinking instead of fans of a "hard Brexit".