Thanks for this brilliant post, Denis!

That GM thing reminds me of a funny routine that happens in France: around the end of the year, firemen and mailmen knock at your door to sell (ugly) calendars. Folk wisdom holds that if you don't buy the calendar, firemen will not rush if there is a fire in your house. Similarly, mailmen will be more likely to lose important mail you receive. What is striking is that this belief seems to carry on though it makes complete non-sense. I bet the situation is a bit different as for GM: the physician obviously remembers you and s/he is more likely to act benevolently towards you with a bit of extra money...

In respect to kinship terminologies, Levinson's question, "What constrains this exuberant diversity of systems?", is not answered by Kemp and Regier's analysis for one simple reason: Terminologies have a structure and logic, like grammars for language, that determine the possible range of kinship terminologies.  Kemp and Regier assume any partition of the space of genealogical relations is a potential terminology and then show that existing terminologies occupy only a small portion of this space due, they assert, to a tradeoff between simplicity and usefulness.  This would be like saying a sentence can be any subset of all possible vocabulary words, then asserting that the realized languages have sentences that are a tradeoff between simplicity and usefulness, but ignoring the fact that the simplicity and usefulness of sentences is created through the grammar of the language that constrains what are admissible sentences.   The same is true for kinship terminologies, and the answer to Levinson's question has already been made by showing that kinship terminologies have a generative structure that determines the corpus of kinship terms, starting from the primary kin terms of a terminology, along with kinship concepts that are expressed in the terminology (such as reciprocity of kin terms), and the kinship structural properties embedded in a particular terminology (Read 1984, 2001, 2007, 2009; Read and Behrens 1990; Leaf and Read 2012, among others).  For example, the difference giving rise to the fundamental division of terminologies into descriptive versus classificatory (bifurcate merging) terminologies derives from two different ways that sibling relations are conceptualized in different societies: (1) a sibling is the child of my parent other than myself (descriptive terminologies) or (2) siblings are those persons who have parents in common (classificatory terminologies) (Bennardo and Read 2007; Read, Fischer and Leaf 2013). Trying to understand kinship terminologies (and hence kinship systems) without first working out the generative logic of a terminology is like trying to understand languages without working out the grammar of a language.  Extensive work has already been published on the generative logic of kinship terminologies and this work makes evident what constrains the variability in kinship terminologies that Levinson asks about.

References

Bennardo, G. and D. Read  2007. Cognition, Algebra, and Culture in the Tongan Kinship Terminology. Journal of Cognition and Culture 7: 49-88.

Leaf, M. and D. Read. (2012)  Human Thought and Social Organization: Anthropology on a New Plane.  Lanham: Lexington Press

Read, D. l984.  An algebraic account of the American kinship terminology.  Current Anthropology 25: 4l7-440

Read, D. 2001 What is Kinship? In The Cultural Analysis of Kinship: The Legacy of David Schneider and Its Implications for Anthropological Relativism, R. Feinberg and M. Ottenheimer eds. University of Illinois Press, Urbana. Pp. 78-117.

Read, D. 2007. Kinship Theory: A Paradigm Shift. Ethnology 46(4):329-364

Read, D. 2009. Another Look at Kinship: Reasons Why a Paradigm Shift is Needed.  Algebra Rodtsva 12:42-69.

Read, D. and C. Behrens. 1990.  KAES: An expert system for the algebraic analysis of kinship terminologies.   J. of Quantitative Anthropology 2:353-393.

Read, D., Fischer, M. and M. Leaf. 2013. What are kinship terminologies, and why do we care? A computational approach to analyzing symbolic domains. Social Science Computer Review 31(1): 16-44.

Dear learned scholar of mathematicians, I disagree with your premise that mathematicians do not disagree, and, being wonderful souls, are easily converted to consensus. No less a scholar, intellectual and role model than Von Neumann (1961), the founder of game theory, argued against your premise. In fact, he bemoaned that unlike physicists, mathematicians who don't agree behave in an unsocial manner by striking out in new directions, leaving their conflicts unresolved. In his article, the first in his collected works, Von Neumann wished that mathematicians disagreed as physicists did. Whenever conflict arose between two physicists (e.g., Bohr and Einstein), physicists refused to ignore it, often bringing their field to a standstill until a resolution was found (i.e., consensus via debate, unlike your fanciful example of consensus without debate). I have long cherished Von Neumann's insight, and his remarkable paper on mathematicians. BTW, in my research, I too have found that consensus without conflict is indeed possible, except that none of the participants can agree on the result. 

Von Neumann, J. (1961). The mathematician. Collected works, Pergamon.

Your hypothesis, Radu, that scam targets personality traits more than they exploit the situations has a corroborating story just out in the news (brought to my attention by Denis Tatone): Paul Frampton, a great physicist, has fallen victim of scam, mistakenly thinking that he was corresponding with a young beautiful model and eventually ending up in jail for transporting 2kg of cocaine.

http://www.nytimes.com/2013/03/10/magazine/the-professor-the-bikini-model-and-the-suitcase-full-of-trouble.html?_r=3&

People concur in saying that Frampton is unusually gullible.

This story of an incredibly gullible scientist (or so it seems) might also be relevant to your remark that the optimality of epistemic vigilance can only be measured in view of its fit to the milieu. An optimal epistemic vigilance would enable people to believe most of the true things they are told and to disbelieve most of the false things they are told (especially the costly one). The inconvincible sceptic as well as the gullible has less than optimal epistemic vigilance. The optimal vigilance fall in between, but its precise position depends on whether the environment is full of false claims or not. It would be interesting to know whether there are different cognitive developments of epistemic vigilance depending on the type of environment in which a child grows up. This could account for some variability across individuals.

As for scientists, they are supposed to instantiate high epistemic vigilance. So how can Frampton be at the same time so gullible and a good physicist? I see two non-exclusive possibilities:

(1) Frampton exercises epistemic vigilance, but only in the domain of physics. This can happen because the scientific environment fosters argumentative abilities. By contrast, Frampton did not wish or need to convince others that he was having a relation with a beautiful model. He did not need to find good reasons for his beliefs and did not wish to adress counter-arguments. Hugo Mercier pointed to me that this difference in the argumentative context could explain the fact that Newton, with so great achievements in physics, did so badly in chemistry/alchemy. There was in alchemy no need to convince others; it was a secret enterprise.

(2) Frampton does not exercise much epistemic vigilance, but does well in physics nonetheless because the process of checking the plausibility of claims is distributed to others. Only very selected information arrives to his creative mind. This is thanks to the process through which scientific information comes to be distributed---the review process for instance. In science, epistemic vigilance is distributed across individuals and institutionalised. In that context, some gullibility might be an advantage. The schoolgirl, in any case, does better by believing the apparently crazy things that her teacher says (e.g. sound is the vibration of matter). At the research level also, it can pay to believe improbable hypotheses; it means pursuing a high risk, high reward research programme.

Thanks Christophe for this engaging reply with a number of very important points!. It is evident that, in both cases, victim’s epistemic vigilance is bypassed by deceivers, but mechanisms of deception are different. Scams exploit mainly individual-level weakness, while fool’s errands use institutional-level affordances. Therefore, their respective strategies of targeting victims are distinct.

Let us suppose that there is a characteristic (or a set thereof) which determines the functioning of epistemic vigilance, and let us suppose that this characteristic varies between individuals. Simply put, some individuals are more gullible than others, everything else being held constant. These individuals are unversed in worldly matters, or they have an inclination to believe everything they are being told, or an inclination to trust everyone. Maybe they present a combination of these features. Among these, only the most gullible ones would fall for a 419 Nigerian scam. (I am referring to current circumstances, not to those of initial scams). You must have never paid attention to web security to have never heard about the scam, and you must be very trusting of people to put your money into their hands, or as greedy as to make you blind to the telltale signs. I’d say you are lot more gullible than almost everyone I know - your characteristics of epistemic vigilance make you a clear outlier.

But victims of fool’s errands are no outliers. Although, (in my estimation) most novice workers fall for the prank, I would consider their epistemic vigilance as entirely warranted by the situation. By warranted, I mean that they are as vigilant as required to function as competent social actors given that they know apprentices should trust their masters, that their technical competence is low and obscure terms will appear in conversations, etc. They know no more and no less than the average novice and are as gullible (in terms of personal characteristics - see above) as the next guy. Moreover, they are as epistemically vigilant when they leave to search for a “pipe-stretcher” as when searching for a “round about” (a real tool with funny-sounding name used for pipelines). What differentiates a fool’s errand from a normal request is the malicious intention of pranksters. The “initiated” know that victims cannot tell the difference between a real and an imaginary tool, that victims trust them with expertise and professionalism, etc. The dice are loaded from the start against the “fool”, and the prankster knows it.

To sum up, I would say that deceivers in each case are angling for different fish in different waters. 419’ers search for the easy prey, the most gullible individuals from an immense pool of unknown recipients. They send out the lure and expect the golden fish, yet know nothing about potential victims. Organisers of fool’s errands are shooting fish in a barrel, since they have control over specific victims in advantageous institutional settings ( distribution of knowledge,structure of command, authority of social roles, etc). This explains the vast difference in success rates between the two forms of deception: one is addressed to millions of users to “capture” a few, the other aims at a handful to ensnare most of them. In order to make the contrast clearer, I venture to say that most people tricked in “fool’s errands” would avoid Nigerian scams. A victim of 419 starting as an apprentice is doomed by the double handicap of institutionalised ignorance and personal gullibility. On a more amusing line, 419 artists would like to replicate the power of fool’s errand practitioners, such as by cracking into the email database of “I am wealthy and I trust unknown people too much” Anonymous.

The interesting theoretical implication suggested by your comment addresses the level at which we evaluate epistemic vigilance. On the one hand, we have the level of personal traits of gullibility. On the other hand, we have the level of structures of knowledge distribution. Can we pry them apart analytically? Empirically, it is problematic since it is very possible that forms of deception take into account both levels. For example, one would not attempt a “fool’s errand” with a highly suspicious apprentice bound to ask questions defusing the prank. Perhaps scammers try to eliminate segments of likely targets according to their web expertise (this is Herley’s argument).

One example comes to mind where both levels are addressed by scammers. On La Rambla in Barcelona, extremely well organised groups of con men play the three card trick. They target individuals with scarce local knowledge - tourists - by using a “touristy” location. However, their hope lies with the most gullible (greedy? drunk? careless?) tourists which can be parted with their money. The population of likely “marks” is selected by con artists (at the level of distributed social competence), while the actual mark selects himself by betting on the rigged game (at the level of individual characteristics).

Sorry for the long reply which mostly stated the obvious and restated in a less concise form your keen observations - but I think there is something theoretically interesting here: is epistemic vigilance only something “in the head”? Or do we need to rely upon an externalist perspective in which levels or mechanisms of epistemic vigilance can only be judged in the context of wider institutions of knowledge production and distribution? On my part, I think future explorations in the latter direction are promising.

P.S. Thinking about gains: fool’s errands are about hearty laughs and humiliating social initiation. Three card tricks aim for the quick buck, 50 euros made in a few minutes, a score of marks per day. 419 target the rare and precious victim, stripped of considerable sums after a prolonged investment in deceptive maneuvers. An association between kinds of gain and kinds of exploited weakness in epistemic vigilance?