Paper Review: The Evolution of Social Norms

I write a lot on this blog about rationality. Not only is it interesting in its own right, but the claim that we are rational creatures has been at the center of western philosophy for millennia, even when under attack. However, regardless of whether or not one thinks we are rational beings, there is one thing that is pretty far beyond reasonable doubt: we are social creatures.

This has also been a core observation of western philosophy. Indeed, Aristotle categorized us among ants and bees as creatures who were fundamentally social. This opens up many puzzles, one of which is how we coordinate our behaviour.
One aspect of humankind which is familiar to all of us, even if sometimes it can fade into the background, just as we become insensitive to a novel smell when exposed to it for a few minutes, is the social norm. Every day we follow plenty of social norms, from how to greet people (shake hands, bow, hug, kiss, etc.), to language, to some of our most fundamental moral positions. We can all think through a host of these norms, and (possibly) think of reasons why they exists — what purpose is it that they serve.

But we don’t want to just understand the norms we have. We also want to understand something about how we ended up with these norms, how they might change, and why different cultures and societies might end up with different norms even when they face similar social challenges. We want a theory of the dynamics of norms. In The Evolution of Social Norms Young shows how evolutionary game theory (which Aydin also wrote about here) can provide a basis for the framework with which we conduct this analysis.

***The original paper can be fond here.***


Young focuses on three things in this article. He identifies certain qualitative aspects of norm dynamics. He then shows how we can formalize these qualitative dynamics using the tools of evolutionary game theory, which in turn can shed light on the qualitative dynamics, and lead to novel predictions. Finally he shows that, despite the limitations of data of real world situations, evolutionary game theory can still help us model and understand real world cases.

For the purposes of this post, I am going to leave aside the second thing, formalizing the dynamics, because of the burdensome technical details. For anyone interesting in the formalization, the original paper provides a nice summary of this area. Instead, in this post I will focus on the qualitative aspects of the dynamics, and a few interesting real world cases Young discusses.

Young’s notion of a norm is very broad, and includes things like “customs, conventions, conceptions of right and wrong, notions of propriety, and regularities of behavior”, ranging “from fine points of etiquette to strong conceptions of moral duty” (p. 361). All of these forms of norms share a few certain features:

1. Norms and behaviors that are self-enforcing at the group level: People want to adhere to the norm if they expect others to adhere to it. …

2. Norms typically evolve without top-down direction through a process of trial and error, experimentation, and adaptation. They illustrate how social order is constructed through interactions of individuals rather than by design.

3. Norms can take alternative forms; that is, they govern interactions that have multiple equilibira. Consequently, they are contingent on context, social group, and historical circumstances.

(p. 361)

The first feature is a kind of stability — norms wouldn’t be able to persist if they didn’t have this feature. The second feature helps show why the first one is necessary for this stability. Far from being planned, most norms arrive spontaneously out of the interactions of many people. In order for these interactions to settle into a specific pattern this pattern of behavior must be desirable, in some sense, for those doing the behavior. The “in some sense” is important: often individuals prefer to do something else (not participate in a duel, for example), but they cannot unilaterally deviate from the norm and be successful. Because of this, norms have some staying power.

Finally, norms are conventional in some sense. What I mean by that is that there are many different possibilities for what form the norm governing an interaction takes. Young writes

Consider the implications of having an illegitimate child, ignoring a challenge to a duel, binding your daughter’s feet, leaving all your property to your eldest son, practicing contraception, keeping a mistress, burping at the end of a meal, or dancing at a funeral. In some societies these would represent serious norm violations; in others, they are perfectly normal practice.

(p. 361)

One of the reasons that norms are self-enforcing at the group level is that there is a host of different mechanisms that enforce normative behaviour. Young lists coordination, social pressure, signaling and symbolism, and benchmarks and reference points as a non-exhaustive collection of enforcement mechanisms. The last two warrant the most explanation.

Signalling and symbolism often involve the way one conveys information useful in a social context to others — things like group membership or intention. Young uses the examples of dress codes signaling group membership.

An example of a reference point is a 50-50 split in bargaining, and an example of a benchmark is the retirement age of 65 in America. Even though many different divisions (65-35) and retirement ages (60, 70) are possible, these points can serve as a heuristic for people to make decisions. There is also an aspect of psychological salience to this; it would seem odd to us to have 68 as the standard year to retire versus 65 or 70.

We can also identify a few key characteristics of how norms change (or don’t over time. Young lists persistence, tipping, punctuated equilibrium, compression and local conformity/global diversity.

We’ve touched on persistence before; it is the phenomena that norms tends to last for long periods, and be fairly resistant to many pressures. Tipping is in some sense the dual to this; it is the well-documented phenomena that when norms do shift the shift tends to be fairly sudden. These two dynamics together lead to the punctuated equilibrium effect. Young uses the example of foot binding in China, where it was common practice for centuries for families to bind the feet of their girls; however the norm disappeared in almost a single generation. Though it lasted a while, once it did shift it shifted fast.

Compression is the phenomenon that people’s behavior exhibit less variation than we would expect in the absence of a norm. For example, consider again the case of the retirement age. Many people do retire at 65, even though people have very different career and financial situations. If there weren’t a norm about retirement age, we would expect larger variation in the age at which people retire. The norm compresses this variation.

Local conformity/global diversity is related to the third characteristic of norms expressed above. Since they can take multiple forms, we see that local communities converge to one norm governing behavior, while when looking at many different communities we see many different norms emerge.

Two of the more interesting norms that Young discusses are dueling and foot binding. For a few centuries dueling was a common upper class practice in Europe. This is particular interesting because it could be very high cost, ending is disfigurement or death. Eventually this norm even spread to the members of the newer professional classes, especially those who had a public image. It is also interesting because it seriously resisted attempts to stop it. I was surprised to learn that “there were nine separate attempts to enforce a ban on dueling in France during the nineteenth century, none of which was successful” (p. 378). This example shows how strong norms can be; even norms that probably everyone from an outside perspective could agree were terrible (no one wants to die) persist.

Young summaries research using evolutionary models that suggest that the two key parts of norm shifts involve the objective cost of the norm (for example, dueling with rapiers is more costly than dueling with broadswords since the former give a higher probability of death), and the social costs of disregarding the norm. The research suggests that this model might account for the different evolution of dueling norms in different areas, where different weapons were used.

The foot binding case seems particular bad to most of us. Young gives a brief history:

Foot binding is an ancient Chinese practice in which a young girl’s toes are bent backward toward the heel and her feet are wrapped in tight bandages to prevent them from growing to normal size. After 5–10 years of painful treatment, the result is a pair of tiny bowed feet that are only three to four inches long. A woman with bound feet cannot engage in most forms of manual labor and cannot walk very far. The custom appears to have originated under the Sung dynasty (960–1279). It was initially applied to concubines in the imperial court and subsequently spread to the upper classes as a sign of gentility. By the Ming dynasty (1368–1644), it had become common practice except among the lower classes where women were needed as laborers. The practice was thought to promote female fidelity, because a woman with bound feet was also housebound.

(p. 377)

It seems that the main mechanism that enforced this norm was that foot binding enhanced a woman’s marriage prospects; thus girls’ families did not want to deviate from this practice. Young describes some research that suggests that the norm stopped due to a sophisticated campaign targeting both boys’ and girls’ families:

A key part of the story is that reformers did not rely on top-down edicts prohibiting the practice; these had been tried repeatedly in earlier times and had come to naught. Instead they organized “natural foot societies” in which families pledged not to bind their daughters and not to allow their sons to marry bound women. In addition, they conducted public campaigns explaining the adverse consequences of foot binding for health, mobility, and employability.

(p. 378)

Young extracts the following lesson from this case:

In other words, they recognized that the key problem was to simultaneously shift the expectations of a group of interacting families, so that it would become rational for them not to continue the practice given its harmful effects and its decreased benefit in the local marriage market. Mackie argues that this approach could serve as a template for displacing other harmful norms, including the practice of female genital cutting in sub-Saharan Africa.

(p. 378)

I think that this last bit is crucial. Understanding both the history and the dynamics of social norms can help us figure out which kind of interventions can be effective (like the campaign targeting multiple groups in the foot binding case) and those that can’t (top-down decrees in the dueling case). Evolutionary game theory can give us insights into successful interventions that can help us change our world for the better.

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