That said, it is worth remembering that the principal architects of the European Union in the 1950s were devout Catholics who understood the principle of subsidiarity as set forth in the social encyclicals of Popes Leo XIII and Pius XI. Out of the debris of the two world wars, Jean Monnet, Robert Schuman, Alcide de Gasperi, Konrad Adenauer, and others sought to build a European federation that would transcend the national antagonisms that had plunged the old continent into conflict twice in thirty years. In so doing, they sought also to move beyond past efforts at unity from a single imperial center. What Napoleon and Hitler had sought to do from the top down the European Union would accomplish from the ground up, at once preserving the best of national autonomy and securing the advantages of greater unity.
We must remember, as well, that the Christian tradition carries within itself, not only the seeds of counter-cosmopolitan localism, but of political universalism, as exemplified in Dante Aligheri's De Monarchia, but even in the old Holy Roman Empire, which claimed some form of preeminence within western Christendom. Reflecting this tradition, the late Otto von Habsburg, son of the last Austro-Hungarian Emperor and King, worked tirelessly for European unity, and very much out of a Catholic worldview.
Moreover, in 1992 the Maastricht Treaty explicitly enshrined the principle of subsidiarity for the future union:
In areas which do not fall within its exclusive competence, the Community shall take action, in accordance with the principle of subsidiarity, only if and in so far as the objectives of the proposed action cannot be efficiently achieved by the Member states and can therefore, by reason of the scale or effects of the proposed action, be better achieved by the Community.
In many respects this principle corresponds to the tenth amendment to the United States Constitution which provides that “The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.” It should be possible for local identities to survive within a larger federal union. The American founders certainly thought so and staked their country's future on it.
Of course, it could be argued that Washington has moved well beyond the powers originally enumerated in Article 1, section 8, encroaching on the prerogatives of the several states in ways not intended by the founders. Across the pond we hear similar arguments that Brussels has violated the spirit of subsidiarity, with the larger dream of unity taking on a life of its own at the expense of the hugely diverse interests of the member states. Hence EU leaders were shocked when French and Dutch voters rejected their proposed European constitution just over a decade ago. And now they are similarly incredulous that any country would want out of the Union altogether, when its benefits seem so obvious to them.
Yet this tale of discontent need not be the whole story. It may well be that future federations will more resemble the Holy Roman Empire or the pre-1848 Swiss confederation than the United States of America or Australia. Canada and Spain have already led the way towards a more asymmetrical federalism in which provinces or regions relate to the federal or central government in different ways. The notion that all component units of a federation must be treated the same is itself an abstraction that may be hindering just governance. If one of your children requires braces on her teeth, you wouldn't think of getting braces for all of your children for the sake of equality of treatment. Similarly, if one state or province aspires to greater autonomy than the others in certain policy areas, granting this in no way undermines just governance and may in fact facilitate it. While formally possessing the same powers as the other provinces as set out in section 92 of Canada's Constitution Act, 1867, Québec in practice exercises certain powers, for example, over language, that the other provinces are content to leave to Ottawa. While Spain is formally a unitary state, Madrid has devolved powers unevenly to its regions, with Euskadi (the Basque region) and Catalunya retaining more autonomy than others.
If we abandon the peculiarly modern quest for strict equality of treatment, it should be possible for the EU to function with its member states unevenly integrated into the whole. A two- or three-tier Union would be the result. France, Germany, Italy and the Benelux countries might be the most tightly integrated federal core of the Union, with no internal border controls restricting the free movement of persons and goods. Other states could remain members of the Union but opt out of some of its integrating features, including the euro zone and the Schengen Agreement. These would retain greater autonomy vis-à-vis Brussels, keeping their own currencies and central banks, along with other markers of independent nationhood.
Such an arrangement may seem terribly untidy and chaotic, but the reality need not be so. If subsidiarity means that as many decisions as possible are made at the lowest levels closest to the people affected, then an unevenly decentralized European Union may, after all, best conform to this principle. If the British people prefer that London (or Edinburgh, Cardiff, or Belfast) take responsibility for matters that the core members prefer to delegate to Brussels, then there is no reason why this should not be permitted. Great Britain could remain part of the EU while, fully in accordance with subsidiarity, claiming as much independence as it needs and can handle.
A bare majority for Brexit is hardly a ringing endorsement of such a momentous move, which threatens to fragment the United Kingdom itself. Better, it seems to me, to opt for both independence and continued membership in the EU, even if it means abandoning the artificial symmetry characterizing the classic modern constitutional federation.
A slightly different version of this is posted at First Thoughts.