Consider trying to predict the details of unattached people’s kisses. That is, you might have data on who such people have actually kissed when, where, and how, and data on who they say they would be willing to kiss under what circumstances. From such data you want to make models of both the kisses that actually happen and the kisses they say they are willing to join. You may notice things like that they kiss more when they are awake, not busy with other activities, and feeling frisky. They kiss more when they and their partner are clean and well groomed. They kiss more when they themselves are more attractive to others, and when other willing partners are more attractive according to this person’s preferences.
Now consider doing the same exercise for people who are married. When you fit sort of data, you will find one big factor that dominates all the others: they almost always kiss only their spouse. Now if you try to explain both these datasets in the same terms, you’d have to say spouses are in some strange way vastly more attracted to each other than they are to everyone else. This attraction is strange because it isn’t explained by objective measurable features you can see, and no one else seems to feel this extra attraction.
Of course the obvious explanation here is that married people typically make a commitment to kiss only each other. Yes there is a sense in which they are attracted more to each other than to other people, but this isn’t remotely sufficient to explain their extreme tendencies to kiss only each other. It is their commitment that explains this behavior gap, i.e., this extra strong preference for each other.
Now consider trying to predict policies and public attitudes regarding limits on who can migrate where, and who can buy products and services from where. And trying to predict this based on the foreseeable concrete consequences of such policy limits. In principle, many factors seem relevant in this case. Different kinds of people and products might produce different externalities in different situations. Their quality might be uncertain and depend on various features. One might naturally want a process to consider potential candidates and review their suitability.
These sort of models might predict more limits on people and products that come from further away in spatial and cultural distance, more limits on versions that have lower quality and higher risks, and more limits when infrastructure exists to make it easier to enforce such limits. And in fact those sort of models seem to do okay at predicting the following two kinds of variation: limits on people and products that move between nations, and limits on people and products that move within nations.
However, if we compare limits between nations and limits within nations, these sort of models seem to me to have a big explanatory gap, analogous to the gap kissing attractiveness models have in predicting married spouses kissing each other. Between nations the default is to have substantial limits on people and products, while within nations the strong default is to allow unlimited movement of people and products.
Yes the context of movement between nations seems to be on average different from movement within nations, and different in the directions that are predicted to result in bigger limits on movement, according to the models we would use to that explain variation between nations and variation within nations. But while the directions make sense, the magnitudes are puzzling and enormous. A similar degree of difference within a nation results in *far smaller limits on the movement of people and products than does a comparable degree of difference between nations.
We are thus left with another explanatory gap: we need something else to explain why people are so reluctant to allow movement between nations, relative to movement within nations. And my best guess here is another sense of commitment: people feel that they have committed to allowing movement within nations, even if that causes problems, and have committed to being suspicious of movement between nations, even if that suspicious makes them lose out on opportunities. That is part of what it means to have committed themselves to a nation.
If this explanation is correct, it of course raises the question of whether this is a sensible commitment to make. For that, we need a better analysis of the benefits and costs of committing to joining nations, an apparently under-explored but important topic.
loading...






