Finally, there is a distinction that matters greatly to economists and a certain sort of political scientist– were voters rational or not? If a voter in the American rustbelt supported Donald Trump because he or she was suffering as a result of international trade, and thought that Donald Trump would be protectionist, then you could view their vote as a rational one. Alternatively, you could view both Donald Trump’s supporters and those who voted in favour of Brexit as having been fooled by unscrupulous politicians. Economists tend to believe that people behave in their own best interests, and in ordinary life it usually makes sense to assume that those with whom you are dealing are going to do what’s best for them. But just because something is usually true doesn’t mean that it always is, and in any event if it is costly to acquire information about the costs and benefits of European integration or globalisation then a rational person may decide to remain ignorant.
People often assume that economic explanations of voting behaviour must imply rational behaviour, but that isn’t so. To be sure, our hypothetical rustbelt voter is voting in his or her own best economic interests, which is what economists tend to define as ‘rational’ behaviour. But what about a hypothetical British voter supporting Brexit because of Conservative Party austerity? It would be difficult to argue that this wasn’t an economic reason to vote for Brexit, but it would hardly be a rational one, given that Osborne’s austerity policies had little or nothing to do with Europe. The UK is not a member of European Monetary Union, nor is it bound by the European Fiscal Compact, nor are the avoidance of excessive deficits and debt and the associated numerical fiscal rules mandated by the Stability and Growth Pact directly binding upon it. George Osborne’s austerity was Made in Britain. If our hypothetical voter supported Brexit because he was unhappy with austerity, he was aiming at the wrong target.
If I were teaching Brexit in 50 years’ time, this is probably how I would introduce the subject. My students would then write essays debating whether the causes of Brexit were cultural or economic, British or international, rational or irrational. These distinctions make pedagogical sense, and they help in understanding what is a complex social phenomenon. But my guess is that, having gone through all the arguments, and assessed all the empirical evidence, and read the authoritative histories of Brexit that would have been written at that point, the conclusion would be that Brexit was complicated, and that all of the reasons mentioned above mattered. Because that is nearly always the conclusion that you reach in questions such as this one.