Let's start with a quick review. We have seen that Judaism is a process which evolves through the interaction of the moral instincts of individuals with established communal moral codes. Since such established codes are themselves the product of individuals' choices, the dynamics are non-linear and can be thrown out of equilibrium. We have seen how this can happen from two different perspectives. The code might lose the necessary balance between community-specific morality and universal morality, with different sub-communities pulling further and further in different directions. More recently we considered the case where a community's belief system – perhaps it would be better to think of it as the narrative a community tells about itself – fails to find a balance between compellingness and plausibility.

Today I want to attack this from a third perspective, namely, the test of community membership. I've talked about individual moral decisions being aggregated into some communal code. That neatly elides a whole lot of funny business about how such codes are really established. Let's try to consider what happens in somewhat higher resolution.

Imagine I've broken my leg and my parents have gotten me a Gramatron electric wheelchair to use on Shabbes. Some doubts have been raised about its permissibility on Shabbes, so I need to make a decision about whether to use it. There are various considerations tied to the specific circumstances of the case (respect for my parents, the extent to which I can manage without the chair) and other more general considerations (established principles of grama on Shabbes, etc.). After analyzing the matter, my instincts might nudge me in one direction or the other. But one extremely central consideration will be my estimate of what the, as yet undetermined, consensus of my community will be on the matter. (Ignore for the moment the question of whether my concern about the emerging consensus is itself a moral consideration or mere cravenness or something in between; we'll get to that.)

How do I go about estimating such a consensus? Some of my friends and neighbors might have thought about the problem and I can canvas them. But I will surely not give them equal weight. Some are more likely than others to be reliable representatives of the emerging consensus. Some are more learned, some are more tuned in, some are more sincere, and some are simply more influential. I'll give these more weight than the others.

Note the circularity here. I'm trying to estimate the consensus based on a sample of people who themselves are trying to estimate the consensus and miraculously a consensus actually emerges from this Keynesian beauty contest. Despite this circularity, I still have a fighting chance to correctly predict the consensus if I assign weights properly. For example, I can assign a great deal of weight to a prominent rov. There are several reasons why the rov's decision has a reasonable chance of predicting the consensus. The most generous explanation is as follows: there is a right answer out there and the consensus is likely to reach it (in accordance with Condorcet's Jury Theorem); similarly, the rov is knowledgeable and unbiased by personal considerations and he too is likely to reach the right answer. A considerably less generous explanation is that the Rov is simply very salient in the community (he is a Schelling point), so that most people are likely to follow his opinion and he will thus determine the (possibly arbitrary) consensus, even if he is just the pin-headed grandson of some obscure Romanian rebbele.

Now just as I want to assign weights to my cohorts in a way that reflects their respective reliabilities, each of my neighbors wants to be assigned high weight by his cohorts. More generally, my neighbor (and I) wish to have status within the community; we want our opinions to matter. But for my opinions to matter, I need to demonstrate at least two things. The first is that I am hooked in to the action in our community; if you give weight to my decisions, you probably won't be left hung out to dry. The second is that I am a reasonably sincere cooperative type, who wants to do the right thing. (My actual real-life neighbor, not the hypothetical one I'm discussing outside these parentheses, thinks only the first of these matters at all; I'm being optimistic.) The problem is that in this transaction between my neighbor and me, there is asymmetric information. I know if I'm hooked in and a reasonably sincere cooperator, but he can only estimate how hooked in I am and he might have a very hard time determining my true commitments; likewise, he knows his own commitments, but I don't.

Such types of asymmetric information are, of course, very common. When you buy a car, the seller knows if it's a lemon, but you don't. When you buy life insurance, you might know that you're a ticking time bomb, but the insurance company doesn't. When you apply for a job, you know that you're brilliant and diligent and not planning to leave for the Amazon as soon as you've finished being trained at your employer's expense, but he doesn't.

In cases of asymmetric information, if you're the person with the informational advantage, you can try to overcome the other guy's suspicions, by signaling that you're a good type. For example, you can spend ten years in college and graduate school. In many fields, your education is pretty irrelevant to your ability to do a good job for your employer, but the fact that you were willing to invest the money and effort to complete the course and were able to do so successfully is a strong signal to a potential employer that you're minimally intelligent and diligent and that, at least when you undertook your course of education, you were sufficiently committed to the field to justify that level of investment.

This kind of signaling is ubiquitous. In the animal kingdom, males signal virility and females signal fertility and each species has evolved so that the relevant signals are instinctively broadcast and instinctively responded to. (The peacock's plumes are a nice example, but big cars and high heels might hit a little closer to home.) What these signals have in common is that they are conspicuous and they are costly, either in terms of money or effort. If education was too easy, it wouldn't be a convincing signal of commitment; if sports cars were cheap, girls wouldn't be impressed.

Let's get back to the shtetl. My status in the community – and, in particular, the weight that others in the community will assign to my decisions in making their own decisions – depends, at least in part, on me signaling that I'm hooked in and want to do the right thing. I need to do arbitrary and costly acts that either would not be worth my while unless I were committed to playing by the rules for the long haul or that somebody who wasn't at the cutting edge of frum fashion wouldn't know about. Conveniently, and not coincidentally, halacha is chock full of opportunities for performing arbitrary and costly acts. Wearing the right clothes, eating the right foods, and performing the right rituals at the right time are all costly and conspicuous. That's a good thing because, precisely because of their conspicuous costliness and arbitrariness, they tell us whom we can trust about issues that might not be arbitrary at all.

If only life were that simple. The effectiveness of signals can vary over time and circumstance. Perhaps once the refusal to eat treif meat or Hostess Twinkies was sufficiently onerous, due to the lack of alternatives, that it could serve as an effective signal. But then the easy availability of kosher meat and snacks rendered such signals ineffective, because they were insufficiently costly. What do you imagine would happen? Well, you don't need to guess because you've seen it happen. The old signals get replaced by new ones that are sufficiently onerous to serve as signals. Kosher is replaced by glatt, which is replaced by chassidishe shechitah, and on up the ladder. The easier each of these becomes, the less useful it becomes.

(When the cost of frumkeit signaling is primarily financial, the signals can be confusing because they are ambiguous. Somehow, I'm never sure if a guy who shvitzes about the leydig-geyer sons and eidims he's supporting in kollel is trying to signal that he's frummer than me or richer than me or both. Is this about religion or is it just garden variety status signaling, in the sense of Veblen? Is there a difference?)

There are some interesting aspects of this kind of signaling escalation that are worth looking at in greater detail. One aspect concerns the splitting off of sub-communities. Different economic and social pressures might result in generally similar communities developing different signaling mechanisms. A shtreimel might be the perfect signal in Romania or Poland, where it is costly but not too costly because interaction with Gentiles is limited, but too onerous in Hamburg, where such interaction is common. So Yekkes and Chassidishe might each inhabit their own separate signaling planets. But then the Poilishers and Romanians develop their own more fine-tuned signals: the Poilishers wear hoiche shtreimels. And they split into Gerrers and Alexanders and Sochaczovers and Amshinovers. And so on. Each of these splits results in a whole new set of increasingly costly signals until the plethora of signals at so many levels of the hierarchy completely drowns out the more basic stuff that still has some connection to moral instincts.

One more point. Most signals are costly only to the signaler. But clearly the signaler regards the cost incurred as justified by the benefit received or he wouldn't bother. For example, wearing a shtreimel is harmless to the rest of the world (except, as my commenters point out, to the sables) and apparently worthwhile to the wearer, so it's a win-win proposition. But there are other signals that negatively impact third parties (an economist would say that there are negative externalities). Think about one particular type of signal called a bridge-burning signal. A familiar example is elaborate body piercing by teenagers. The way this works is that a conspicuously pierced teenager has few options in the adult world because s/he is liable to be shunned by respectable types and hence signals that s/he is a reliable cooperator in the rebellious teenager sub-community. In our context, draft evasion in Israel or failing to get an education in the U.S. are conspicuous examples of bridge-burning signals. Each of these is very costly to the signaler because it cuts off many options for advance outside one's sub-community and hence signals long-term cooperation within the community. But, unlike wearing a shtreimel, it is also socially costly, because it imposes a greater burden on those outside the community, who need to pick up the slack.

Now, imagine escalating signal wars as various sub-sub-communities distinguish themselves in which the ever-more-costly signals also happen to be bridge-burning signals with significant negative externalities. Now that is a recipe for disequilibrium.