Do you know any Catalans who do not have an opinion on the matter of independence? Me neither. Virtually everyone has made up their mind on it. There are two groups: those for, and those against. As is the case with other divisive issues (gay marriage in the 1990s, for example), the third “undecided” group is a tiny minority.

When it comes to divisive issues, people rarely change their mind. The convinced are no longer convincible. Opinions become fossilized, and the advocates of an opinion interpret new information in a way that supports their already held convictions (ie, confirmation bias). Research shows that people irrationally cling to their beliefs, once they decide something. In fact, there is some evidence to suggest that presenting people with information which contradicts their opinions actually causes them to believe even more firmly in those opinions.

Let’s assume then, for the foreseeable future, that Catalans will not change their minds on the question of independance. The half in favor will remain in favor; the half opposed will remain opposed. What do you think will happen?

If you guessed “infinite gridlock”, you’re likely wrong. Even if no attitudes change, social majorities will change. How? 3 reasons:

  1. People die.
  2. People move.
  3. People are born.

In other words, as politicians yell at each other trying (unsuccessfully) to convince the opposing side to adopt their viewpoint, a process much more powerful than politics is taking place in the background: demography. Minds changing is not the driver of many radical social changes; rather it is populations changing. To return to our previous example of gay marriage, the reason it has been legalized in so many western countries in recent years is not because those who staunchly opposed it changed their minds; rather, it is because those who staunchly opposed it got old and died. The same phenomenon largely explains other social changes, such as the rise in feminism and environmentalism, or the declines in racism and anti-semitism. At the individual-level, very few people change their mind on these issues. But at the collective level, societies change when the young come to age and the old pass on.

Those interested in the future of Catalonia should take into account demography. Birth rates and migration have changed radically in recent decades, and the effects of these changes will linger for generations. There is no way to be certain about the future – unknown future economic and social forces will impact mortality, migration, and fertility – but we can use the information available now to predict the future.

This article aims to do just that: quantify the effect that demographic changes in Catalonia will have on support for Catalan independence.

Background: which demographic factors affect support for independence

The reason that demographic change will bring about social change in Catalonia is because demographic characteristics are closely associated with support for independence. Two factors are especially relevant: age, and place of birth.

The below chart shows the association between place of birth and support for independence. Catalans in born in Catalonia are largely in favor of independence. Catalans born elsewhere are largely opposed to it.

And the below shows the association between age and support for independence. Young Catalans are largely in favor of independence, whereas older Catalans are largely opposed.

Let’s dive into the details.

Describing the present

There is an important demographic trend taking place right now in Catalonia: the percentage of Catalans who were born in Spain is decreasing. One can only speculate whether this trend played a role in the rapid increase in support for independence in recent years, but the data are clear – over the last 20 years, the percentage of Catalans born in Spain decreased from 27.2% to 16.6%.

Why has the percentage of Catalans born in Spain decreased? It’s not because they are leaving Catalonia to return to Spain. Rather it’s because the Spanish-born population of Catalonia is far older than the average population of Catalonia. The below chart shows the distribution of the age of Catalans by place of birth:

Note in the chart above how in the right-most planel, data are clumped higher, whereas in the left-most and central panel, data are distributed lower. Most Catalans who were born in Spain are old: whereas the median age of Catalans born in Catalonia is 38 and the median age of Catalans born in the rest of the world (not counting Spain) is 37, the median age of Catalans born in Spain is 64. Three-quarters of Catalans born in Spain are 55 or older.

In other words, the decrease in the percentage of Catalans who were born in Spain is due largely to mortality, not emigration.

Why does this all matter? Because the old, here and everywhere, will continue to die before the young. And unless the migration patterns of the future are identical to the migration patterns of the past (which they almost certainly willl not be), these deaths will leave a mark on collective political preferences.

Predicting the future

With its current demographic make-up, Catalonia is split approximately 50-50 on the question of independence. Let’s see what is likely to happen in a few years.

The below shows what will happen to Catalonia’s current population over time. Since most Catalans who were born in Spain are older, their share (as a percentage of the total Catalan population) will decrease over time.

If we examine only mortality (ignoring, for the moment, migration and fertility), Catalonia’s population by place of birth would look like this over the next few decades.

Note the difference in the grey (abroad) and green (Spain) lines. Though the percentage of Catalans who are born in Spain vs. born in the rest of the world are similar now (approximately 17-18%), they will diverge sharply in the near future. The reason why is because foreign-born Catalans are relatively young compared to Spanish-born Catalans.

The result of these differences in ages is this: even if nobody changes their mind, the percentage of Catalans in favor of independence will increase steadily over the next few decades. Because so many anti-independence Catalans are elderly, support for continued union with Spain will decrease steadily as the elderly pass away. The below shows the estimated percentage of Catalans in favor and opposed to independence, assuming (a) opinions don’t change and (b) only mortality (not migration and fertility) affect the population structure.

Is it reasonable to assume that there will be no new births and no new migration to or from Catalonia in the future? Of course not. Just as people (sadly) cease to exist, so too can they be created. Birth is one way. The other way (at least for our purposes) is migration.

Even though it is impossible to predict the future of migration and births, it is wrong to ignore them. So, for this exercise, we’ll simply make some assumptions: that the number of annual births in Catalonia will remain the same as now (or rather, 2017, the most recent year for which data is available), and that the number of migrations (both to and from Spain and the rest of the world) will remain constant as well (using the average from the period of 2005 to 2017)

With these assumptions made, Catalonia’s population looks like this over the next few years:

What effect will this have on support for independence? The below shows estimated support for independence, assuming no changes in opinions, future migration rates identical to those of the last 10 years, and future birth rates identical to that of 2017. The effects of demographic change will be seen, even in the short-term:

In other words, even if ZERO people change their minds, the 50-50 split will not continue.

Still, there’s one more adjustment we need to make. The above plot shows the likely outcome of a yes/no independence referendum, assuming that all Catalan adults were permitted to vote. As ideal as this might be from a democratic perspective, it’s unlikely to be the case. Specifically, most Catalans who were born abroad are not citizens of Spain (there are many exceptions, of course), and assuming that a future referendum were held in accordance with Spanish legislation, they would not be permitted to cast a vote.

So, for our final chart, let’s see what would happen in a hypothetical referendum taking into account only those who are likely to be able to vote (those born in Spain/Catalonia). The result is below.

What does the above show? That the forces of demography alone will result in support for independence reaching 60% in 2039, even if nobody changes their opinion on the matter.

Conclusion

Time is working against those who oppose Catalan independence. Catalans who were born in Spain – a bastion of support for the Spanish unionist movement – are largely elderly and are being replaced by younger Catalans born in Catalonia (largely in favor of independence) and younger Catalans born abroad (who, for the most part, cannot vote). Regardless of your opinion on independence, these are the facts.

I argue in this article that minds rarely change, and I believe firmly that this is the case for most political issues. It is for this reason that demographic change is important to understanding Catalonia’s future. With fossilized opinions on both sides, it is unlikely that there will be any major “conversions” in near-term.

That said, unlikely does not mean impossible. Minds do ocasionally change on some issues. Perhaps a Spanish Government will propose a political settlement which is acceptable to a majority of Catalans (so far this hasn’t happened). Perhaps Catalans will grow tired of seeking independence, and will settle for some modified version of their current autonomy. Or perhaps some freak event will change the entire conversation.

But barring the above, the most likely course of events is this: the Catalan independence movement will continue to grow in numbers, and a Spanish Government (perhaps not the current one, since its official position on Catalan self-determination is “no is no, never is never”) will be forced to recognize the political reality and work for a political solution. A solution almost certainly involves a referendum on independence and – unless minds radically change in the coming years – this referendum will be won by the pro-independence camp.

Technical note

This article contains many projections, which – like all projections – are almost certainly inaccurate. Though actuarial science is fairly accurate (life expectancies, etc.), forecasting migration and fertility is largely a guess. For the purposes of transparency, all code and data used for this article is publicly available online.