I know some people who advocate open borders. They seem to think that if there were no restrictions to the flow of goods and people between countries, everything would somehow sort itself out. There would be no illegal immigrants, no detention centres, no long queues at passport control, and the law of supply and demand would smooth out the bottle necks. If one part of the world was especially attractive to people, it would become so intolerable because of the huge influx of people, that it would cease being popular and people would move elsewhere.

I’ve never met anyone who advocated the opposite, which is to say closed borders. But I suppose they must exist. Most people, though, are somewhere on the spectrum between open borders at one end and closed borders at the other. Indeed, this goes for all kinds of borders, not just national ones. Some people seem to be temperamentally more comfortable with clearly defined boundaries, whereas others seem to prefer a more amorphous, flexible existence.

It appears that conservatives are generally more into boundaries than liberals. They seem to like to see everything in its proper place. They will be less inclined to blur the boundaries between the sexes for example. They will be less likely to blur age boundaries and act like a teenager in their forties. They will prefer their art in a frame on the wall rather than on the floor. They will probably eat lunch and dinner at lunch-time and dinner-time.

There is no such thing as open borders or closed borders, open boundaries or closed boundaries. They are always semi-permeable, although the degree of permeability varies. Obviously, the phrase “open boundary” is a contradiction in terms. If it is fully open, it doesn’t classify as a boundary. A “closed boundary” also implies that it can be opened or traversed. If it were completely impenetrable, it wouldn’t make sense to call it a boundary.

There is an Overton window through which we can see the range of reasonable permeability or porosity of any particular boundary, such as a national border. Within this window, it is possible to have a range of views on exactly how open or closed it should be.

Outside this reasonable mid-range, however, are the outliers who would like to see a much more open border on the one hand or a much more closed one on the other. These go far beyond the conservatism of the conservatives or the liberalism of the liberals. I call these outliers muppets.

There are four types of muppet: nerds, fundamentalists, hippies and radicals representing the two opposite poles of the border debate.

Nerds can only function within very clearly demarcated boundaries. They need parameters within which to make sense of the world. They are highly methodical logicians. They tend to be somewhere on the autism spectrum. They may display obsessive or compulsive behaviours. They write in short sentences.

Fundamentalists are similarly highly boundaried. They draw very thick lines between people and things. There is a clear division between the in-group and the out-group. Ideas are literally true or literally false. There is no room for ambiguity or nuance. There is no room for poetry or metaphor. They know the difference between right and wrong and no amount of argumentation will budge the high wall between them.

Hippies are the opposite. They believe that “all is one” and train themselves not to even see the divisions between things. They float around without caring about right and wrong or up and down or left and right. They believe that they have entered a New Age, where everything melts into everything else. All religions are the same. Everything is permitted and everything is cool.

Radicals are less laid-back. They are also on the open borders of the spectrum, but only because they see so much division in the world. Instead of just ignoring borders and boundaries like the hippies do, they spend their time and energy tearing them down. Any social distinction between different classes of people is seen as inherently divisive and oppressive. They are therefore extremely sensitive to class, race, culture, gender, sexuality, socio-economic status, and any other dimension along which people can be distinguished. Any distinction between people is ultimately seen as a form of segregation imposed by a power-hungry elite.

This is how the muppets fall: nerds and fundamentalists on the extreme of the closed borders end of the spectrum and hippies and radicals on the extreme of the open borders end. Everyone else is somewhere in the middle. Of course we all need borders and boundaries, whether physical or psychological, but it’s best if they’re not too many or too high. We need limits, but within limits. We should take everything in moderation, including moderation.