How I Learned to Stop Worrying and Love the Bomb

bomb

Orbital Mechanics has created an incredibly creepy, yet riveting video showing every single nuclear detonation from 1945 onward.

 

You would be excused if your first reaction is “holy shit, we’re absolutely bonkers.” That was my first reaction.

My second thought was: “we were lucky that, aside from the obvious first two bombs, we were relatively lucky in that nothing ever went wrong.” But I was wrong to think that – nuclear testing led to long lasting, negative effects on the cognition of people who were exposed to the radiation while in utero. Sandra Black and co. have a really interesting paper examining the effect on Norwegians (apparently due to atmospheric conditions, a large hunk of radiation form nuclear testing landed in Norway):

Research increasingly shows that differences in endowments at birth need not be genetic but instead are influenced by environmental factors while the fetus is in the womb. In addition, these differences may persist well beyond childhood. In this paper, we study one such environmental factor – exposure to radiation –that affects individuals across the socio-economic spectrum. We use variation in radioactive exposure throughout Norway in the 1950s and early 60s, resulting from the abundance of nuclear weapon testing during that time period, to examine the effect of nuclear exposure in utero on outcomes such as IQ scores, education, earnings, and adult height. Importantly, we are able to examine the effects of exposure each month in utero to determine the periods when exposure is most harmful. We find that exposure to low-dose nuclear radiation, specifically during months 3 and 4 in utero, leads to a decline in IQ scores of men aged 18. Moreover, radiation exposure leads to declines in education attainment, high school completion, and earnings among men and women. We are also able to examine whether these effects persist across a second generation – we find that the children of persons affected in utero also have lower cognitive scores, suggesting a persistent effect of the shock to endowments. Given the lack of awareness about nuclear testing in Norway at this time, our estimates are likely to be unaffected by avoidance behavior or stress effects. These results are robust to the choice of specification and the inclusion of sibling fixed effects.

Hat tip to Kottke.

 

The IMF, inequality and the trickle-down of empirical research

"It took so many assumptions to put you together!"

“It took so many assumptions to put you together!”

By Nicolas Van de Sijpe

recent IMF staff discussion note has received a lot of attention for claiming that a smaller income share of the poor lowers economic growth (see also here and here). This piece in the FT is fairly typical, arguing that the paper “establishes a direct link between how income is distributed and national growth.”

It quotes Nicolas Mombrial, head of Oxfam International’s office in Washington DC, saying that (my emphasis): “the IMF proves that making the rich richer does not work for growth, while focusing on the poor and the middle class does” and that “the IMF has shown that `trickle down’ economics is dead; you cannot rely on the spoils of the extremely wealthy to benefit the rest of us.”

The aim of this blog post is to clarify that the results in Table 1 of  the paper, which are based on system GMM estimation, rely on assumptions that are not spelled out explicitly and whose validity is therefore very difficult to assess. In not reporting this and other relevant information, the paper’s application of system GMM falls short of current best practices. As a result, without this additional information, I would be wary to update my prior on the effect of inequality on growth based on the new results reported in this paper.

The paper attempts to establish the causal effect of various income quintiles (the share of income accruing to the bottom 20%, the next 20% etc.) on economic growth. It finds that a country will grow faster if the share of income held by the bottom three quintiles increases. In contrast, a higher income share for the richest 20% reduces growth. As you can imagine, establishing such a causal effect is difficult: growth might affect how income is distributed, and numerous other variables (openness to trade, institutions, policy choices…) might affect both growth and the distribution of income. Clearly, this implies that any association found between the income distribution and growth might reflect things other than just the causal effect of the former on the latter.

To try to get around this problem, the authors use a system GMM estimator. This estimator consists of (i) differenced equations where the changes in the variables are instrumented by their lagged levels and (ii) equations in levels where the levels of variables are instrumented by their lagged differences (Bond, 2002, is an excellent introduction). Roughly speaking, the hope is that these lagged levels and differences isolate bits of variation in income share quintiles that are not affected by growth or any of the omitted variables. These bits of variation can then be used to identify the causal effect of the income distribution on growth. The problem with the IMF paper is that it does not tell you exactly which lagged levels and differences it uses as instruments, making it hard for readers to assess how plausible it is that the paper has identified a causal effects.

Continue reading

Guns don’t kill people

commando

Think of all the cultural reasons I am wielding this rocket launcher.

Another shooting happens. This time in Charleston. I grew up about two hours away and often visited the town with my parents. It’s a lovely place, although like most places in South Carolina it has a difficult, disturbing past.

There are two opposing views which typically surface after  a mass shooting. The first is that gun violence is driven by gun ownership, and that effective gun control will reduce the number of people killed by firearms every year.  A simple mathematical way of describing this relationship would be to say that gun violence is a function of the number of guns in a country:

V = F(G)

The opposing view is that there are all sorts of other things that determine gun violence. Proponents look to countries with high levels of gun ownership but low levels of violence, such as Canada. Holders of this view assert a relationship that looks like this:

V = F(S)

Where S is “other stuff” which influences gun violence. This is somewhat consistent with the  “guns don’t kill people, people kill people” argument, which includes the unstated third statement: “and there are lots of things that determine whether people want to kill each other.”

Setting aside any preoccupations with the Second Amendment, the gun control debate can be characterized as a fight over whether V = F(G) or V = F(S). But this is a mischaracterization which gives more legitimacy to those opposed to gun control. In reality, gun violence is a function of both the number of guns in circulation and all the “other stuff,” and that, by construction, fewer guns makes it more difficult to commit gun violence, so that.

V = F(G,S) and V = 0 if G = 0 or S=0

That is: it doesn’t matter if Canada can have its cake and eat it. If there is some special ingredient to having guns without the violence (S = 0), we don’t know what it is, and won’t know any time soon. But that doesn’t mean that reducing G will not reduce violence. Whether it is a cost-effective way to reduce violence is another question, but unless someone identifies what goes into S, the best bet is for the US to focus on G.

LaTeX Wars Episode V: The Word Users Strike Back

Of course I edit all my documents using the original Nintendo Power Glove

Of course I edit all my documents using the original Nintendo Power Glove

Throughout the mid-90s, my father used a DOS-based typesetting program called PC-Write to produce his books and journal articles. In stark contrast to more-popular word processing programs, PC-Write relied on a what-you-get-is-what-you-mean approach to typesetting: dad would indicate his formatting preferences as he wrote, but he would be forced to print out a page in order to see his formatting options being applied. By contrast, I grew up working with Microsoft Word and so with each passing year I found my father’s system to be increasingly archaic. Eventually, after a substantial amount of healthy mockery from his son, he migrated over to Word and hasn’t looked back since.

However, by the time I arrived in grad school an increasing number of other (economics) students were using LaTeX, a typesetting language that was much closer in design to the old-fashioned PC-Write than to the what-you-see-is-what-you-get format of Word. Although I suspected that LaTeX was another manifestation of the academic economist’s tendency to choose overly-complex methods and technical mastery over user-friendliness, I eventually became a convert. Somehow, I found my preferences begun to mirror Dad’s original love of PC-Write.

If you ever feel like experiencing a wonderfully-arbitrary argument, ask a group of economists if they prefer LaTeX or Word. Within the profession there is a pretty serious division between those who prefer the look and workflow of the former  and those who prefer the accessibility of the latter. While there are some of us who are comfortable working in both formats, each camp has its stalwarts who find members of the other camp to be bizarrely inefficient.

The two sides appeared to be in a stable stalemate until recently, when a new study comparing the efficiency and error rates among LaTeX and Word users appeared in PLOS One. The headline result: Word users work faster AND make less errors than LaTeX users.

journal.pone.0115069.g004

Ooof – I hear the sound of a thousand co-authors crying out with righteous indignation. The Word camp was quick to seize upon this study as clear evidence that LaTeX users were probably deluding themselves and that now would be a good time for everyone to get off of their high horse. The authors of report  even went as far to suggest that LaTeX users were wasting public resources and that journals should consider not accepting manuscripts written up using LaTex:

Given these numbers it remains an open question to determine the amount of taxpayer money that is spent worldwide for researchers to use LaTeX over a more efficient document preparation system, which would free up their time to advance their respective field. Some publishers may save a significant amount of money by requesting or allowing LaTeX submissions because a well-formed LaTeX document complying with a well-designed class file (template) is much easier to bring into their publication workflow. However, this is at the expense of the researchers’ labor time and effort. We therefore suggest that leading scientific journals should consider accepting submissions in LaTeX only if this is justified by the level of mathematics presented in the paper.

Pretty damning, eh? Not so fast! There are several reasons we should doubt the headline result.

For one, rather than randomly assigning participants to Word or LaTex, the researchers decided to allow participants to self-select into their respective groups. On one hand, this makes the result even more damning: even basic Word users outperformed expert LaTeX users. The authors themselves admit that preference for the two typesetting programs varied wildly across disciplines (e.g. computer scientists love LaTeX and health researchers prefer Word). It’s perfectly possible that the types of people that select into more math-based disciplines are inherently less efficient at performing the sort of formatting tasks set by the researchers. Indeed, the researchers found that LaTeX users actually outperformed Word users when it came to more complex operations such as formatting equations.

Furthermore, the researchers only evaluated these typesetting programs along two basic dimensions: formatting speed and error-rates, ignoring other advantages that LaTeX might have over Word. As an empirical researcher, I find it enormously easier to link LaTeX documents to automated data output from programs like Stata, making it simple to update results in a document without having to copy and paste all the time. Word can also do this, but it has always been far clunkier.

So, in short, the jury is still out. Feel free to return to your respective camps and let the war continue.

Protected by randomness

tdh2

From fusion.net:

The Random Darknet Shopper, an automated online shopping bot with a budget of $100 a week in Bitcoin, is programmed to do a very specific task: go to one particular marketplace on the Deep Web and make one random purchase a week with the provided allowance. The purchases have all been compiled for an art show in Zurich, Switzerland titled The Darknet: From Memes to Onionland, which runs through January 11.
The concept would be all gravy if not for one thing: the programmers came home one day to find a shipment of 10 ecstasy pills, followed by an apparently very legit falsified Hungarian passport– developments which have left some observers of the bot’s blog a little uneasy.

The title of the piece (Robots are starting to break the law and nobody knows what to do about it) elicits worries of AIs gone amok, but the basic conundrum of this piece and others about the Random Darknet Shopper is more complex: if I design an AI which takes a random, blind action in a space which is largely – but not uniformly – illicit, am I legally culpable?

Take this thought experiment: imagine going around your office with a ten dollar bill, offering to buy whatever your colleagues would be willing to sell to you at that price, but under the condition that you do not see the item until the transaction has taken place. If one of your colleagues slipped you some cocaine, who would be at fault? What if you chose to repeat the experiment in an area of town infamous for drug-deals, are you suddenly more culpable?

When I was young, I used to order what they called “Grab Bag” comic packs, where I would pay a set amount of money for an unknown, random assortment of comic books. If someone had slipped a pornographic comic into my grab bag, it’s hard to see how I would be at fault. But where I choose to make my blind transactions seems to augment how we perceive culpability.

Several years ago I wrote a piece about how randomness can complicate our standard notions of guilt. The intersection of randomness, culpability and the law sounds like an area that – if someone hasn’t written about it a lot already – is ripe for further work.

Branko Milanović and the Spam King of Development

monfort3

A few weeks ago, I received a bizarre e-mail addressed indirectly to former World Bank economist and inequality/wealth guru Branko Milanovic. An excerpt:

Marry me, CUNY Prof. Branko Milanovic. Become part of our family of Expert Dreamers. Join the Serbia Strategic Team and help us design, create, imagine a Wonderful future for Serbia, for the World and for the Sollar System.

Yes I am positive. I want to become President of the Sollar System before 2050 with you in our team. Yes I am positive. I want to contribute my best efforts, to devote my lifetime to this wonderful challenge. And I want you, CUNY Prof. Branko Milanovic, I want you to come with me, to come with us.

Following this e-mail, a slew of my colleagues and I began to receive e-mails requesting that we receive chapters for a book known as “The Monfort Plan,” a sort of grand scheme to end global poverty by assembling a team of “Expert Dreamers” to essentially act as the world’s largest peer review body. A bit like The Avengers but without all the charisma and one-liners.

The source of these e-mails was a man named  Jaime Pozuelo-Monfort – or `JP Monfort’ as he likes to call him self. JP Monfort is a professional development spammer. As described on his bio for the Huffington Post (further proof that the only binding prerequisites for bloggers at HufPo are a hindbrain and access to a keyboard), Monfort has six or seven masters degrees in a variety of economics or finance-related subjects, although he apparently has yet to learn of the concept of diminishing returns.

Monfort is infamous for his frequent spamming of university departments and research institutes, either to recruit scholars to join his team of Expert Dreamers or to rope people into reviewing his inane book chapters. This incessant behaviour has actually resulted in not one, but four entire threads dedicated to him at econjobmarketrumors.com, a website which itself will likely confirm any suspicions you might have that economics comprises a disconcertingly-large number of self-obsessed sexist, racist, socially-inept douchebags. If you’re in the mood for a little more entertainment, JP Monfort has a slew of videos online in which he mumbles through various aspects of his master plan – awkward, amateurish productions set in bizarre locations such as the side of a road or what appears to be a swimming pool shower. He also has an online site dedicated to “The Clinton Letters”, chronicling correspondence between him and Bill Clinton, which appears to amount to standard brush-off replies from the latter’s office, including a thank you for the Monfort Plan t-shirt that was sent his way.

His book is currently available on Amazon, although plagued by one-star reviews from irate academics targeted by his e-mails. One reviewer notes:

 While I can’t comment on the content of the book, if it’s anything like the vague, grandiose drivel I receive weekly in my inbox, I doubt it has anything practical to say about modern economic, social, and political problems…

Indeed, from reading the book chapters he has sent my way, it is difficult to discern whether Monfort is deluded, a scam artist, or some sort of weird meta-troll. His prose is circular and vague, nonsensical but coherent enough to pass for an NGO report. Some sections are devoted to describing – essentially paraphrasing – the of work other mainstream development experts, including Milanovic himself, Daren Acemoglu and our own Nancy Birdsall, rather than contributing anything new to the development debate.  Chapter 29 of the seemingly-never-ending, rambling book describes the role of the “Chief Dreamer” (inevitably Monfort himself) who would be in charge with leading the way in the fight against world poverty:

“The Chief Dreamer must remain awake while others sleep, must work in the interest of the developing world and propose forward-looking ideas that are realistic so that the reader find sufficient matter to employ his or her speculations for the rest of her life. The Chief Dreamer must be a twenty-first century Jules Verne who conquers through persuasion and not imposition. The Chief Dreamer must combine the qualities of George Kennan and Jean Monnet and be determined to defend the priorities of the vulnerable. The Chief Dreamer must be multilingual to address a variety of audiences in different geographies and must be multidisciplinary to understand the complex roots that drive today’s increasing inequality gap and inequality.”

The only novelty in the book is born out data generated by the sheer number of people Monfort has managed to piss off. You see, so many people have requested to be removed from the ever-growing list of Expert Dreamert that Monfort dedicates an entire segment of his book to analysing the breakdown of which academic disciplines are most likely to click unsubscribe:

I soon realized academics were overwhelmingly requesting to be removed from The Decem List. The trend was so notorious that I decided to create this subsection to express a concern. There is a subset of academia who may be reluctant to embrace a new economic paradigm, as it relies on new ideas not supported by the orthodox theories that for decades have been feeding the intellect of university professors from the world’s best universities.

expertnd

I’m curious as to what it is about Mr. Monfort’s incoherent ramblings that appeals more to anthropologists and agricultural engineers than to economists, psychologists and sociologists. Alas, it will remain one of life’s great mysteries.

Oh, by the way, Mr. Monfort could you please drop me from your mailing list?

The Twelve Days of Christmas (Aid Edition)™

It’s an oldy but a goody, and the only thing I always  repost. Go on, sing along:

On the twelfth day of Christmas my donors gave to me

twelve delayed disbursements!

eleven sketchy studies

ten consultants calling

nine economists arguing

eight mission meetings

seven worthless workshops

six gender trainings

five RCTs!

four 4x4s

three acronyms

two empty schools

and a lecture on M&E!

Still on sale.

Who you gonna call? A mob

stoning

“Look, I’d had a lovely supper, and all I said to my wife was: “That piece of halibut was good enough for Jehovah.” “Blasphemy! “”

Large crowds are inherently scary. Not, perhaps at first glance, but those of us that live in large cities do so under the assumption that while crowds are somewhat chaotic  and have the potential for danger, they will never be intentionally malevolent, at least not towards us. Yet there is still an unease there, of the type that underlies the kind of horror frequently employed in post-apocalyptic zombie films or John Carpenter flicks, that very quickly the crowd can turn against you.

Perhaps this is not totally unreasonable source of anxiety – while most violence in London (where I’ve recently started living) tends to be of the individual-on-individual sort, mob violence is more frequently a reality for many living in developing countries. Take, for instance, this new report by the incredibly prolific NGO Twaweza on violence in Tanzania. Drawing upon a nationally-representative phone survey, one of the most striking results is deaths due to mob violence appear to be more common (or are as commonly-perceived by respondents) than ordinary murders: twaweza

In fact, as many people are killed by mobs as by ordinary citizens, police and the national army combined. If we consider mob violence to be a form of extra-legal justice, imagine a government which executes more people than those who commit murder. While these figures are based on perceptions and should be taken with a grain of assault, it’s worth noting that forensic investigations into violent deaths in Dar es Slaam reveal that at least 10% are due to mob justice, still a staggering number.

Yet, outside of the occasional hushed ex-pat dinner party conversation or resigned lamentations by locals, I’ve rarely hear people actually discuss the causes and consequences of mob violence in much detail (although as I write this I suspect that a reader will soon point out that something akin to a Journal of Mobbing Studies which I will have overlooked). Malawi, where I lived for some, seemed particularly afflicted with mob violence centred around automobile accidents, where the drivers of cars found to be at fault were often assaulted, and sometimes killed. This happened with enough frequency to create a culture of “fleeing the scene,” where drivers who were not even directly connected to an accident drove off for fear of being blamed and attacked (this was the basis for a film I shot whilst living there). I began thinking about the issue again when, recently, one of the respondents in a survey I’m helping run in Dar es Salaam was killed by a mob after (purportedly) murdering another resident. 

What leads to mobbing and why does it appear to be more prevalent in societies with dysfunctional institutions? Let’s take the armchair economist position for a moment: it would probably be fairly easy to write down a herding model where people update their beliefs about a person’s guilt based on the behaviour of others. Person 1 decides, for whatever reason, that the accused is guilty, person 2 updates his/her beliefs based on person 1’s belief, and so on, until you have a mob which is convinced that the accused is guilty. If you combine that with a utility function that inversely weights the disutility or ‘guilt’ one might feel  from being personally responsible for a death (I take comfort in knowing I probably didn’t throw the fatal stone), it’s easy to see how mobs might easily form in a context where punishment would otherwise be uncertain.

While this sort of explanation is rather intuitive, I find it a bit unsatisfying for three reasons: i) it ignores the drivers of the probability of punishment in the counterfactual and ii) it assumes that mob behaviour is solely defined over the desire to inflict justice on the guilty. It also tells us nothing about why people are more likely to be stoned to death in Dar es Salaam than, say, Myrtle Beach. A couple of thoughts:

i) What happens if we don’t stone people to death? Most socio-cultural explanations share a similar premise: people rely on mob violence precisely because they do not trust the formal justice system to get the verdict right. If the police and judiciary are capable of finding and punishing the right person, our need to rely on selection-via-herding decreases. If this is true, then strengthening the formal justice system should reduce mob violence. This falls apart if people can selectively engage the formal system – if mob justice isn’t just about guaranteeing some form of punishment, then perpetrators may still choose vigilantism over bringing in the police. This brings me to the next thought:

ii) Is this really about punishment? As with most social/political/economics concepts, Monty Python got there first: in Life of Bryan overzealous women disguise themselves with fake beards so they can throw stones at people for the fun of it. If mobs are primarily made up of young angry men, then we might begin to suspect this has more to do with the tendency for young, angry men to enjoy a bit of the ultra-violence.

Is there a quick fix here, other than waiting for the legal system to become strong enough to both reasonably guarantee punishment of those that commit the initial crime and those who engage in mob justice? Given the snowballing nature of mob violence, moving quickly to both disrupt the initial signal (that the accused must be guilty) and raise the cost of participation (a less extreme version of the Desmond Tutu method of mob justice defusal, perhaps). Do we need a roving band of mob-busters to save the day?

Or perhaps it is reasonable that mob justice is so infrequently subject to policy discussion – it is something which probably declines as countries get richer and their institutions grow more robust, so is it really deserving of too much scrutiny? 

Math fail

jumpstreet

Until  my early 20s, I never knew that one could become good at math. In high school, I ended up failing 10th-grade math.

That’s Marc Bellemare discussing his struggles with learning mathematics in high school and undergrad. For those of you don’t know, Marc is now an economics professor and is comfortable enough with math to write theory-heavy journal articles. His story about grappling with the subject and eventually learning to master it is well worth a read, especially for those who believe they are inherently bad a math.

I didn’t struggle with mathematics for quite as long as Marc did, but was nearly dissuaded at a much earlier age by the tyranny of early math education: arithmetic.

I’ve never been particularly good at adding, subtracting, multiplying or dividing. How much should we leave for a tip? I’ll let my calculator decide. It’s no surprise then that I found math in elementary school so daunting: we were required to do randomised times tables,where we had to answer as many addition/multiplication questions as possible before an alarm clock went off. I found this immensely stressful and found it very difficult to remember what 7 x 13 was when I knew that any minute now a clock was going to go BZZZZZZZ (I sense there has been a generational improvement though: my father noted that his math classes at a Roman Catholic seminary involved the lecturer smacking students in the back of the head until they got the question right).

When I go back and look through my elementary report cards, I can see how poorly I did: Cs and Ds in basic math, with worried remarks by teachers. Clearly math wasn’t my thing.

Then I was introduced to algebra. You see, arithmetic was usually taught as an exercise lesson: you don’t think about what 7 x 13 means, you remember it. But once math becomes more abstract, it becomes more conceptual and substantially less about memory. I loved algebra. In fact, I loved algebra, trig, and calculus so much that I went on to major in math in university, where I eventually semi-defected to the economics department.

Readers of this blog will probably be past the point where they make significant choices about their math education, but something to keep in mind when you have kids: it’s incredibly easy to be discouraged by math, especially in the early days when it is more about memorization. Others struggle with the more abstract stuff, but as Marc points out, this is a better reason to double down, rather than abandon it for good.*

 

*Obviously this should only be done to a point – everyone has comparative advantages.

Immigration smimmigration

"If you choose the red pill, then I'll show you just how deep the rabbit hole goes. But then we're going to stop releasing people from the Matrix. We're worried about wage effects in Zion."

“If you choose the red pill, then I’ll show you just how deep the rabbit hole goes. But then we’re going to stop releasing people from the Matrix. We’re worried about wage effects in Zion.”

Paul Collier writes about immigration for Bloomberg. I’m sure we’re only a matter of minutes away from some very serious commentary from the folks at CGD or from Roving Bandit, but here are a few of my own thoughts.

Firstly, Collier argues that new immigration inevitably will hurt the status of the recently-migrated, even if it does not hurt the native population:

The answer is that those who have already migrated lose, at least in economic terms, through the subsequent migration of others. Migrants lose because they compete with one another.

Migrants aren’t in close competition with indigenous workers. The advantage the indigenous have may be that they have better command of the language or that their greater tacit knowledge of social conventions makes them more productive.

The effects of immigration on the wages of indigenous workers vary between very small losses and modest gains. If immigration policy were to be set by its effects upon wages, the only interest group to campaign for tighter restrictions should be immigrants.

The individual behavior of immigrants evidently belies this interest: Immigrants typically devote considerable effort to trying to get visas for their relatives. But these two interests aren’t inconsistent.

An immigrant who enables a relative to join her receives benefits such as companionship. The increased competition in the job market generated by the extra migrant is suffered by other immigrants. In effect, a tightening of immigration restrictions would be a public good for the existing immigrant community as a whole.

So immigration doesn’t hurt the`indigenous’ population, but will hurt new migrants? Solution: every country in the world allows just one immigrant in its borders, then closes them forever. Seriously, it is unclear here what Collier’s assumed social welfare function is.* It’s perfectly understandable why immigration restrictions might be endogenous to levels of migration, but I’m struggling to recall any high-profile cases of recent-migrants calling for a curb on future migration.**

If we cared about general welfare and not just that of recent migrants, loosening restrictions are a bit of a no-brainer. Yes, it might depress wages in the short run for other migrants (evidence?) but compared against the enormous welfare benefits from the migration itself, this is really a second-order concern (a bit like arguing that we shouldn’t let anyone else into the life-boat because, damn it, it will be less comfortable).

Next, Collier argues that new immigration creates another set of externalities on existing migrants: more hate

There may be further social reasons that the existing stock of immigrants has an interest in tighter restrictions. The size of the immigrant stock also affects attitudes of the indigenous population. Contrary to the hope that exposure increases tolerance, the opposite appears to happen.

Heightened intolerance is a public bad suffered by immigrants as a whole, and is thus inadvertently generated by the individually maximizing migration decisions of each successive migrant. Hence, the paradox of migration. Individual migrants succeed in capturing the huge productivity gains from migration. But migrants collectively have an interest in precisely what individually is most detrimental: entry barriers.

Haters gonna hate – and haters gonna hate even more when there are more immigrants around, apparently. Again, no evidence is given to support this case. While I do think there is a worthwhile conversation to be had about how immigrants integrate into societies and how best to maintain social cohesion, falling back on the “We, the indigenous, are inherently racist, and are just going to get more racist as more foreigners show up and there’s nothing to be done about it” argument seems a bit silly.

Finally, Collier argues that migrants might not actually be that much happier and that, combined with the psychological cost of being in a new culture, immigration might be a bad deal. He turns to evidence from several studies showing happiness doesn’t increase when people are allowed to migrate.

This seems to me to be a better argument against using happiness as a welfare indicator, rather than against migration itself. It also leaves us with an entirely unsatisfactory explanation for current migration: that people are deluded about the benefits and would have preferred never to have traveled in the first place. This is particularly hard to swallow in an era where information is particularly cheap – it is relatively easy to send information back to one’s friends and family to clarify that, actually, it isn’t as cool here as I thought it was going to be.

In general, these feel like highly theoretical, armchair rationales for limiting migration. Surely we’ve moved past this by now?

 

*Update #1: To clarify, I mean the SWF Collier is using to make his case, not necessarily his personal preferences over migration!

**Update #2: a friend noted (via e-mail) that this is historically quite common – waves of immigrants turn around and try to stop the next group from landing. While I’d conceded that former-immigrants tend to resist those coming from a different national/ethnic origin, are there any cases where immigrants tried to close the door on immigration from their own country of origin?