Dunbar’s Number

One of my favorite ideas in social science is Dunbar’s number: the cognitive limit to the number of relationships our brains can handle. It’s something like 150. That’s about the number of people our ancestors might have shared their tribe with 20,000 years ago.

Our sense of social propriety is tuned to dealing with people within our circle. Economics often seems counter-intuitive because it’s largely about how to interact with people outside that circle.

Here’s the example I use in class:

You’ve got a date tonight. You stop at a florist to pick out a bouquet and start wondering if maybe chocolate would be a better gift. Dark chocolate or milk? Or maybe something else. You think back to your economics classes and realize that if your date had $20 cash, they could buy this bouquet if it’s what they really wanted, or chocolates if that’s preferred. So when you knock on the door, instead of offering a bouquet, you hold out a crisp $20 bill.

What happens next?

If you aren’t dating an economist, you get the door slammed in your face.

So you run back to the florist, buy the flowers, run back, and nobody answers the door. Your date probably went to the bar with friends. You call a cab. When it pulls up to your door, the fare is $20. You just spent $20 on these flowers. You try to pay for your fare with the flowers.

What happens next?

The driver refuses and insists on cash.

So what’s better, flowers or cash? Is your date irrational, or the cab driver? Neither. Both are rational within the context they’re acting in. The driver is a stranger and market rules are appropriate. In this context, $20 is worth more than $20 worth of flowers. Maybe the cab driver wants flowers, but cash gives them the option to buy whatever best meets their needs.

You and your date were trying to cease being strangers. The cab driver is outside of Dunbar’s number, but your date would have (could have) been inside that inner circle. At that point, the signaling value of the flowers would trump the economic value of the cash.

Economics has a lot to tell us about how to behave with those inside and outside of our Dunbar’s number. But that dividing line calls for different rules on either side: the rules of family and neighbors on one side, and the rules of the market on the other.

I’m thinking about Dunbar’s number because I just finished a recent episode of EconTalk where they talked about a classic example from behavioral economics: An Israeli daycare, tired of late pickups started charging fines to late parents. Ironically, this resulted in an increase in late pickups that persisted even when the policy was reversed.

The daycare example is often trotted out to say “see! Sometimes adding an incentive backfires! Raising the price from $0 to $x increased the quantity of lateness demanded. People are irrational!” Of course it only takes about 5 seconds of thinking to realize that we aren’t holding all else equal here. As usual, there’s a lot of interesting stuff hidden in the ceteris paribus assumption.

The more sophisticated interpretation of this example is that attaching a price shifted parent’s interpretations of the norms. In my language: the inclusion of money in that interaction shifted the rules of behavior from those of neighbors to those of strangers.

(Roberts brought up an important point I hadn’t considered with this example: the price was too low. Prices communicate information about how onerous it is to produce a product, and that price told parents “it’s not a big deal if you’re late…”)

More generally, when we’re looking at some social scientific question, Dunbar’s number demarcates a point separating the assumptions we can make about sharing and monitoring–whether it’s about the practicability of communism (the real kind, not the kind with mass murder), corporate bureaucracy and firm size, or the tenability of informal institutions.

Nightcap

  1. An anticipatory elegy Walter A. McDougall, Law & Liberty
  2. Colonial lives of legality Alvina Hoffmann, Disorder of Things
  3. The limits of interdisciplinarity Nick Nielsen, Grand Strategy Annex
  4. Should we federalize the social sciences? Michelangelo Landgrave, NOL

Legal Immigration Into the United States (Part 7): An Exemplary Social Science Attempt to Disentangle

Using estimations of the relationships between several sets of good data to infer causation is an old endeavor, of course. The difficulties to which I pointed above are not new. For a little over one hundred years, the social sciences have emerged largely with the mission to solve or circumvent such difficulties. Their efforts have been broadly productive; inferences of causation based on quantitative estimations that respect state-of-the-arts social science rules are more trustworthy than practically everything else. In brief, the more complex the issues under study, the more back-of-the-envelop calculations suffer in comparison with modern social science methodology. Issue of comparative immigrant vs native born criminality are pretty much at a level of complexity for which those methods were developed.

The rules of social science include an obligation to publish in scholarly journals where the findings will be subjected both to pre-publication and to post-publication critical assessment. (See my didactic essay on scholarly submission: “What’s Peer Review and What it Matters) Publication in scholarly journals also facilitates eventual attempts at replication with its potential to root out major research-based fallacies. I realize that duplication is a rare event, but the threat of it keeps researchers on their toes. Note: This doesn’t mean that the degree of confidence one should award to serious social science products should be high, in absolute terms. There is a difference in practice between, “bad,” and “very bad.” Also, in spite of formidable recent successful hoaxes against pseudo-journals, some disciplines hold the line, including left-leaning Sociology. (Read Gabriel Rossman’s “Sokal to the Nth Degree” in the November 8th-11th issue of the Weekly Standard.)

As it happens, there is a recent study that addresses the topic of immigration and criminality that fulfills good social science criteria. It’s Michael T. Light and Ty Miller, “Does Undocumented Immigration Increase Violent Crime?” published in Criminology, March 3, 2018. The study relies on data from all 50 states plus the District of Columbia, collected from 1990 to 2014, inclusive. Its design is reasonable; it allows for the observation of change over time in the relationships of interest. The 24-year period of observation is a convenience sample of any longer period one would prefer, but it’s not known to what extent it is representative of a longer period. This is a common limitation on interpretation. Twenty-four years of observation is a lot better than one year for the purpose of generalization though. The estimation methods used in their study to express the relationship between numbers of illegal immigrants, on the one hand, and several well accepted measures of serious criminality, on the other, are up-to date. The same methods allow for the elimination of alternative formulations – that is, they allow for “controlling” for variables other than the main variable of interest, the number of illegal immigrants. The article contains a useful and thorough review of the literature. It’s written with remarkable clarity, given the inherent complexity of the endeavor it describes.

The study gives a straightforward answer to the straightforward question it poses:

The increase in the number of illegal immigrants (in the US) is associated with a decrease in serious crime.

The authors dispose fairly well of an interpretation of these counter-intuitive findings based on the idea that more illegals results in less crime reporting in the relevant populations, rather than in actual decrease in crime. This explanation would make their startling main finding practically spurious.

It is not equally clear to me that the authors have disposed completely of the hypothesis that an influx of illegal immigrants is causally linked to stepped-up law enforcement, and only thence to crime reduction. This formulation has important policy implications. It says: Illegal immigration does not increase crime, provided you do what needs to be done about it. And, you may be lucky and overshoot your mark. Ideally, I would  have liked to see a measure of cost per some unit of crime reduction included in the estimation models.

It’s unfortunate for my purpose that this study focuses on illegal immigration specifically, since my own primary interest is in legal immigration. It matters little in the end because a secondary analysis within this study indicates that increase in legal immigration (considered separately from illegal immigration) is also associated with a decrease in serious crime.

As quantitative social scientists are unfortunately inclined to do, Light and Millet give us a literal expression of their main finding, like this (I think this practice, of making findings shout instead of whispering should be heavily taxed.):

A one-unit increase in the proportion of the population that is undocumented corresponds with a 12 percent decrease in violent crime.

We don’t have to take literally this metric wording and the causality it suggests. For example, there is no need to believe that if enough additional illegal immigrants enter the US, at some point, serious crime will disappear completely. It’s enough to acknowledge that a very good study on the relationship between immigration and serious crime leaves little room for the possibility that the more of the one, the more of the other.

Note, however, that the Light and Miller findings do not exclude this formulation completely. It’s possible that in some states an increase in illegal immigration is associated with a surfeit of serious crime. It’s possible even that for all states, but for a brief period, an increase in illegal immigration is quickly followed by a rise in serious crime. Because of these possibilities, the public perception and the startling results of this study may well be compatible. These would probably not be casually detected. Few regular observers, be they politicians, journalists, or public servants are likely to have a clear view of events in 51 separate entities sustained for twenty-four years. Intelligent, rigorous minded observers may be right about what they know and drastically wrong about what they have not studied through hard facts.

Light’s and Miller’s is a classically good article. It’s thorough without sacrificing detail; it offers a good quality and a useful review of the relevant sociological literature; it’s tightly reasoned. The estimations it reports on seem impeccable. I think Light and Miller is the standard against which all reports on the relationship between immigration and crime should now be assessed. Practically, this article should contribute to switching the burden of proof: Although they are less educated, poorer, and younger on average than the native-born population, immigrants appear to commit less serious crime than the latter. More surprisingly to some, illegal immigrants, who begin their American career by demonstrating their willingness to violate American law, do not appear to be prone to criminal violence.  But, as I have mentioned before, an illegal status is a strong incentive to keep one’s nose clean.

I am not proposing here that Light and Miller’s article should forever block the progress of more conventional ideas  to the effect that more immigration is associated with more crime. All it would take would be a single study of similar quality to overturn this remarkable study’s findings. In the meantime, it would be reasonable to shift the burden of proof  away from where it has implicitly stood: immigrants tend to be criminal.

[Editor’s note: in case you missed it, here is Part 6]

On the rift between economics and everything else

The line is often heard: economists are “scientific imperialists” (i.e. they seek to invade other fields of social science) jerks. All they try to do is “fit everything inside the model”. I have this derisive sneer at economists very often. I have also heard economists say “who cares, they’re a bunch of historians” (this is the one I hear most often given my particular field of research, but I have heard variations involving sociologists and anthropologists).

To be fair, I never noticed the size rift. For years now, I have been waltzing between economics and history (and tried my hand at journalism for some time) which meant that I was waltzing between economic theory and a lot of other fields. The department I was a part of at the London School of Economics was a rich set of quantitative and qualitative folks who mixed history of ideas, economics, economic history and social history. To top it all, I managed to find myself generally in the company of attorneys and legal scholars (don’t ask why, it still eludes me). It was hard to feel a big rift in that environment. I knew there was a rift. I just never realized how big it was until a year ago (more or less).

There is, however, something that annoys me: the contempt appears to be self-reinforcing.  Elsewhere on this blog (here and here) (and in a forthcoming book chapter in a textbook on how to do economic history), I have explained that economists have often ventured into certain topics with a lack of care for details. True, there must be some abstraction of details (not all details are useful), but there is an optimal quantity of details. And our knowledge grows, the quantity of details necessary to answering each question (because the scientific margin is increasingly specialized) should grow. And so should the number (and depth) of nuances we make to answer a question.  There is a tendency among economists to treat a question outside the usual realm of economics and ignore the existing literature (thus either rushing through an open door or stepping in a minefield without knowing it).  The universe is collapsed into the model and, even when it yields valuable insights, other (non-econs) contributors are ignored.  That’s when the non-econs counter that economists are arrogant and that they try to force everything into a mold rather than change the mold when it does not apply. However, the reply has often been to ignore the economists or criticize strawmen versions of their argument. Perceived as contemptuous, the economists feel that they can safely ignore all others.

The problem is that this is a reinforcing loop: a) the economists are arrogant; b) non-economists respond by dismissing the economists and ridiculing their assumptions; c) the economists get more arrogant. The cycle persists. I struggle to see how to break this cycle, but I see value in breaking it. Elsewhere, I have made such a case when I reviewed a book (towards which I was hostile) on Canadian economic history. Here is what I said for the sake of showcasing the value of breaking the vicious circle of ignoring both sides:

These scholars (those who have been ignored by non-economists) could have easily derived the same takeaways as Sweeny. Individuals can and do engage in rent-seeking, which economists define as the process through which unearned gains are obtained by manipulating the political and social environment. This could be observed in attempts to shape narratives in the public discourse. According primacy to the biases of sources is a recognition that there can be rent-seeking in the form of actors seeking to generate a narrative to reinforce a particular institutional arrangement and allow it to survive. This explanation is well in line with neoclassical economics.

This point is crucial. It shows a failing on both sides of the debate. Economists and historians favorable to “rational choice” have failed to engage scholars like Sweeny. Often, they have been openly contemptuous. The literature has evolved in separate circles where researchers only speak to their fellow circle members. This has resulted in an inability to identify the mutual gains of exchange. The insights and meticulous treatments of sources by scholars like Sweeny are informative for those economists who consider rational choice as if the choosers were humans, with all their flaws and limitations, rather than mechanistic utility-maximizing machines with perfect foresight (which is a strawman often employed to deride the use of economics in historical debates) . In reverse, the rich insights provided by rational choice theorists could guide historians in elucidating complex social interactions with a parsimony of assumptions. Without interaction, both groups loose and resolutions remain elusive.

See, as a guy who likes economics, I think that trade is pretty great. More importantly, I think that trade between heterogeneous groups (or different individuals) is even greater because it allows for specialization that increases the value (and quantity) of outputs.  I see the benefits of trade here, so why is this “circle of contempt” perpetuating so relentlessly?

Can’t we just all pick the 100$ bill on the sidewalk?

Lunchtime Links

  1. David Reich’s essay in the New York Times on genetics, race, and IQ
  2. Henry Farrell’s essay at Crooked Timber on genetics, race, and IQ
  3. Ezra Klein’s essay at Vox on genetics, race, and IQ
  4. Chris Dillow’s essay at Stumbling and Mumbling on genetics, race, and IQ
  5. Andrew Sullivan’s essay at Daily Intelligencer on genetics, race, and IQ

Andrew’s essay is a must read. It’s careful, well thought out, and bolder than the other ones. All are well-worth reading, though.

Reich’s essay has sparked an important dialogue in the Anglo-American world (props to the NY Times). Globally, I think conceptions of race, genetics, and IQ in the non-Anglo world are based on pseudoscience (at best), so it’s nice to see this debate unfold the way it has (so far).

I don’t think any of them have done a good job grappling with Charles Murray’s argument. (More on that later.)

Thanks to Uncle Terry for bringing this to light in the first place.

The selfish meme

There are two senses in which to consider the phrase.

  1. The sense in which memes enter or exit our minds.
  2. The sorts of behavior encouraged by our memes.

For those who don’t know what I’m talking about:

A meme (/ˈmm/ meem)[1] is “an idea, behavior, or style that spreads from person to person within a culture”.

Richard Dawkins introduced the idea in his famous book: The Selfish Gene. The bulk of his book discusses examining the gene as the basic unit of analysis in evolutionary studies. He introduces the idea of the meme as a different form of replicator. Both genes and memes will only be reflected in the outcome of biological and cultural evolution if they exhibit fitness–if they are able to survive.

So the cultural traditions that helped hunter-gatherer societies survive droughts or harsh winters tended to survive and spread. Over time a culture accumulates this sort of practical, tacit knowledge. (Side note: this week’s Econtalk has Cesar Hidalgo who does really interesting work trying to indirectly measure the presence of such tacit knowledge in market economies.) And if culture is made up of memes, the same way organisms are made up of genes.

Looking at genes as the unit of analysis (as opposed to the organism) explains some otherwise mysterious behavior. It provides a plausible explanation of altruism: we care for our children more than anyone because 50% of their genes are our genes. A nephew is still precious, but not as important to us because the expected ratio of shared genes between the two of you is 25%. A gene that prompts you to protect your children is likely to survive longer than a gene that doesn’t prompt you. (And genes that hang around with such kin-protects genes are also more fit than their competition.) A gene that prompted you to be kind to neighbors makes sense when you live in small groups. But a gene that prompted you to be kind to total strangers might be a liability in a world where strangers were dangerous.

Cultural evolution certainly makes sense as a gradual mutation of different cultural practices merging together to make what is called (and perceived) as a unique body of culture. It’s a complex of knowledge, ideas and basic assumptions, social interface protocols, and it’s deeply embedded in how we engage in the world. (Perhaps we can’t remember our infancy because we didn’t have a cultural lens through which to reference anything to anything else…) One thing that I’m sure we’ve all noticed is that it can be almost painful to have to reject a cherished belief. It’s even difficult to see one of these memes challenged.

Now genes don’t have to be small bits of genetic code. They can be something simple like “make this enzyme when you get a chance.” But as a unit of replication, you should consider the smallest discrete chunk of genetic coding that replicates itself. If a particular pattern isn’t fit, it will leave the gene pool, while the fit collections of genetic instruction spread. So you might end up with long complex strings of genetic material akin to a computer program. Initially simple scripts might gather as successful collections of genes that work well together. The “produce stomach acid” gene works well with the “produce a stomach” gene and soon the two are virtually inseparable. They’ve become a simple script: “Do this, then that, then maybe this other thing.” Scripts gather into multi-cellular organisms with different functions that can respond differently to different stimuli. Soon you’ve got a complex set of code as your replicating unit.

More complex genes are necessary to prompt more complex behavior. It’s worth noting that Dawkin’s theoretical framework sometimes looks like a hyper-rational economics model. Evolutionary Stable Strategies are a Nash Equilibria that are robust to invaders. They occupy a niche and survive. But this evolution is happening in the context of increasing complexity. The system is learning*. This isn’t an instantaneous process**, but it is gradually becoming more sophisticated.

A complex gene will get bugs due to random mutation, but as long as it’s still generally fit, it will survive. And over time, more subtle and sophisticated programs identify new niches. And we get plant genes surviving by filling the “eat sunlight” niche and animals in the “eat plants” niche, and bacteria co-evolving with animals’ digestive systems.

Slowly working through this long, blind, random process genes surviving this hostile environment develop behaviors that help them flourish (the “four F’s of evolution: Fighting, fleeing, feeding, and reproduction”). Gradually they stumble into opportunities, and an important one was social behavior.

More and more complexity, round and round, until we start to get our first little bits of sentience. I’ve been watching a chinchilla hop around my apartment for a couple weeks now and I’m astonished by how much effort she puts into genuinely exploring her world. She tests objects for structural integrity and learns what she can and can’t jump on. She tests boxes with her teeth, I don’t know what for. She’s distinctly learning and not merely existing or surviving. She’s comfortable and does not know fear (I’ve seen her scare one particularly wussy cat). That sort of behavior requires a great deal of complexity which requires a great deal of genetic material.

I’m noticing as I write this that the biggest gene (i.e. discrete, replicated set of genetic code) must be that very large collection of genetic patterns that must come together in order for a one’s offspring to simply be the same species.*** I’ve heard that humans and chimps share 94 percent of our genetic material. That overlap tells me that some larger percentage than that is what makes us actually a human. The difference between any two individuals, then, must be among a very small portion of their total genetic makeup. This small portion is where genetic competition occurs in the arena of sexual reproduction.

In any case, our first memes (behaviors) seem to be transmitted biologically. Later, with more complex genes, we are able to replicate more complex behaviors. Eventually, we get complex enough to build up a sense of consciousness****.

A complex enough gene might have a subroutine that sets off an error; something like the pain our consciousness experiences when things are going poorly*. And likewise for a meme. Though more likely is that the error is being returned by our psychology. (If our genes are assembly language, our psychology is the operating system, and culture is the mess of basic programs that makeup our desktop environment.)

When we think of memes as self-replicating units, interesting questions arise: what sort of patterns will be robust to competition? Which will occupy what niches? What happens when incompatible memes come together in one mind? What sort of eusocial behaviors are possible? How much do our memes govern our behavior? (This is where nature and nurture overlap.)

Obviously one possibility is a “selfishness meme,” or a culture that hits an equilibrium of distrust. But there are many others, and how they combine matters. At this level we’re essentially asking questions about psychology, culture, and institutions. The fodder of all the social sciences comes together here. Different memes will be transmitted in different ways (which is perhaps what defines the disciplines), but any of these memes may be complex enough to have a defense mechanism that involves activating various processes (including other memes, perhaps) and perhaps making people feel anger and related emotions when someone questions our beliefs and may even push people to fight with their life for their memes.


*We’re computers, markets are computers, societies are computers, the ecosystem is a computer, Earth is just a big giant computer. It processes data and creates new data.

** The next Hayek rap should include the phrase “it’s spontaneous order, not instantaneous…”

*** I could imagine it as made up of some set of smaller genes in some complex, rather than one monolithic gene but I don’t have the language to communicate that idea concisely.

**** And it must be noted that this consciousness is built out of parts designed for the poop-and-panic machines that were our evolutionary ancestors. It’s like building a super computer* out of a truck load of Pez dispensers and a warehouse full of chainsaws. And yet, how else could it be done.

Federalizing the Social Sciences

A few days ago I asked whether the social sciences could benefit from being unified. The post was not meant to make an argument in favor or against unification, although I myself favor a form of unification. The post was merely me thinking out loud and asking for feedback from others. In this follow up post I argue that the social sciences are already in the process of unification and a better question is what type of unification type this will be.


What is a social science?

First though allow me to define my terms as commentator Irfan Khawaja suggested. By social sciences I mean those fields whose subjects are acting individuals. For the time being the social sciences deal with human beings, but I see no particular reason why artificial intelligence (e.g. robots in the mold of Isaac Asimov’s fiction) or other sentient beings (e.g. extraterrestrials) could not be studied under the social sciences.

The chief social sciences are:

Economics: The study of acting individuals in the marketplace.

Sociology: The study of acting individuals and the wider society they make up.

Anthropology: The study of the human race in particular.

Political Science: The study of acting individuals in political organizations.

There are of course other social sciences (e.g. Demography, Geography, Criminology) but I believe the above four are those with the strongest traditions and distinctive methodologies. Commentators are more than encouraged to propose their own listings.

In review the social sciences study acting individuals.  A social science (in the singular) is an intellectual tradition that has a differentiating methodology. Arguably the different social sciences are not sciences as much as they are different intellectual schools.


Why do I believe the social sciences will be unified? 

On paper the social sciences have boundaries among themselves.

In practice though the boundaries between the social sciences blurs quickly. Economists in particular are infamous for crossing the line that the term ‘economics imperialism‘ has been coined to refer to the application of economic theory to non-market subjects. This imperialism has arguably been successful with Economists winning the Nobel prize for applying their theory to sociology (Gary Becker), history (Douglass North, Robert Fogel), law (Ronald_Coase) and political science (James M. Buchanan). The social sciences are in the process of being unified via economic imperialism.

Imperialism is a surprisingly proper term to describe the phenomenon taking place. Economists are applying their tools to subjects outside the marketplace, but little exchange is occurring on the other end. As the “Superiority of Economists” discusses, the other social sciences are reading and citing economics journals but the economics profession itself is very insular. The other social sciences are being treated as imperial subjects who must be taught by Economists how to conduct research in their own domains.

To an extent this reflects the fact that the economics profession managed to build a rigorous methodology that can be exported abroad and, with minimal changes, be used in new applications. I think the world is richer in so far that public choice theory has been exported to political science or price theory introduced to sociology. The problem lays in that this exchange has been so unequal that the other social sciences are not taken seriously by Economists.

Sociologists, Political Scientists, and Anthropologists might have good ideas that economics could benefit from, but it is only through great difficulty that these ideas are even heard. It is harder still for these ideas to be adopted.


Towards Federalizing the Social Sciences

My answer to economic imperialism is to propose ‘federalizing’ the social sciences, that is to say to give the social sciences a common set of methodologies so that they can better communicate with one another as equals but still specialize in their respective domains.

In practice this would mean reforming undergraduate education so that social science students take at minimum principle courses in each other’s fields before taking upper division courses in their specializations. These classes would serve the dual purpose of providing a common language for communication and encouraging social interaction between the students. Hopefully social interaction with one another will cause students to respect the work of their peers and discourage any one field from creating a barrier around itself. A common language (in the sense of methodology) meanwhile should better allow students to read each other’s work without the barriers that jargon terminology and other technical tools create. It is awful when a debate devolves into a semantics fight.

Supplementary methodologies will no doubt be introduced in upper division and graduate study, reflecting the different needs that occur from specialization, but the common methodology learned early on should still form the basis.

The unification of the social science need not mean the elimination of specialization. I do however fear that unless some attempt is made in ‘federalizing’ the social sciences we will see economics swallow up its sister sciences through imperialism.

As always I more than encourage thoughts from others and am all too happy to defer to better constructed opinions.