Sender–receiver games, first introduced by David Lewis ([1969]), have received increased attention in recent years as a formal model for the emergence of communication. Skyrms ([2010]) showed that simple models of reinforcement learning often succeed in forming efficient, albeit not necessarily minimal, signalling systems for a large family of games. Later, Alexander et al. ([2012]) showed that reinforcement learning, combined with forgetting, frequently produced both efficient and minimal signalling systems. In this article, I define a ‘dynamic’ sender–receiver game in which (...) the state–action pairs are not held constant over time and show that neither of these two models of learning learn to signal in this environment. However, a model of reinforcement learning with discounting of the past does learn to signal; it also gives rise to the phenomenon of linguistic drift. 1 Introduction2 Dynamic Signalling Games with Reinforcement Learning2.1 Introducing new states2.2 Swapping state–action pairs3 Discounting the Past3.1 Learning to signal in a dynamic world3.2 An unexpected outcome: linguistic drift4 ConclusionAppendix: A Markov Chain Analysis. (shrink)

This paper examines two questions about scientists’ search for knowledge. First, which search strategies generate discoveries effectively? Second, is it advantageous to diversify search strategies? We argue pace Weisberg and Muldoon (2009) that, on the first question, a search strategy that deliberately seeks novel research approaches need not be optimal. On the second question, we argue they have not shown epistemic reasons exist for the division of cognitive labor, identifying the errors that led to their conclusions. Furthermore, we generalize the (...) epistemic landscape model, showing that one should be skeptical about the benefits of social learning in epistemically complex environments. (shrink)

Consumer involvement in clinical research is an essential component of a comprehensive response during emergent health challenges. During the COVID-19 pandemic, the moderation of research policies and regulation to facilitate research may raise ethical issues. Meaningful, diverse consumer involvement can help to identify practical approaches to prioritize, design, and conduct rapidly developed clinical research amid current events. Consumer involvement might also elucidate the acceptability of flexible ethics review approaches that aim to protect participants whilst being sensitive to the challenging context (...) in which research is taking place. This article describes the main ethical challenges arising from pandemic research and how involving consumers and the community could enable resolution of such issues. (shrink)

It is certainly the case that morality governs the interactions that take place between individuals. But what if morality exists because of these interactions? This book, first published in 2007, argues for the claim that much of the behaviour we view as 'moral' exists because acting in that way benefits each of us to the greatest extent possible, given the socially structured nature of society. Drawing upon aspects of evolutionary game theory, the theory of bounded rationality, and computational models of (...) social networks, it shows both how moral behaviour can emerge in socially structured environments, and how it can persist even when it is not typically viewed as 'rational' from a traditional economic perspective. This book also provides a theory of how moral principles and the moral sentiments play an indispensable role in effective choice, acting as 'fast and frugal heuristics' in social decision contexts. (shrink)

Multiarm bandit problems have been used to model the selection of competing scientific theories by boundedly rational agents. In this paper, I define a variable-arm bandit problem, which allows the set of scientific theories to vary over time. I show that Roth-Erev reinforcement learning, which solves multiarm bandit problems in the limit, cannot solve this problem in a reasonable time. However, social learning via preferential attachment combined with individual reinforcement learning which discounts the past, does.

At the very end of the 19th century, Gabriele Tarde wrote that all society was a product of imitation and innovation. This view regarding the development of society has, to a large extent, fallen out of favour, and especially so in those areas where the rational actor model looms large. I argue that this is unfortunate, as models of imitative learning, in some cases, agree better with what people actually do than more sophisticated models of learning. In this paper, I (...) contrast the behaviour of imitative learning with two more sophisticated learning rules (one based on Bayesian updating, the other based on the Nash-Brown-von Neumann dynamics) in the context of social deliberation problems. I show for two social deliberation problems, the Centipede game and a simple Lewis sender-receiver game, that imitative learning provides better agreement with what people actually do, thus partially vindicating Tarde. (shrink)

Rachlin's idea that altruism, like self-control, is a valuable, temporally extended pattern of behavior, suggests one way of addressing common problems in developing a rational choice explanation of individual altruistic behavior. However, the form of Rachlin's explicitly behaviorist account of altruistic acts suffers from two faults, one of which questions the feasibility of his particular behaviorist analysis.

In the course of history, many individuals have the dubious honor of being remembered primarily for an eponym of which they would disapprove. How many are aware that Joseph-Ignace Guillotin actually opposed the death penalty? Another notable case is that of Maria Agnesi, an Italian woman of privileged, but not noble, birth who excelled at mathematics and philosophy during the eighteenth century. In her treatise of 1748, Instituzioni Analitiche, she provided a comprehensive summary of the current state of knowledge concerning (...) both integral calculus and differential equations. Later in life she was elected to the Bologna Academy of Sciences and, in 1762, was consulted by the University of Turin for an opinion on the work of an up-and-coming mathematician named Joseph-Louis Lagrange. (shrink)

Evolutionary game theoretic accounts of justice attempt to explain our willingness to follow certain principles of justice by appealing to robustness properties possessed by those principles. Skyrms (1996) offers one sketch of how such an account might go for divide-the-dollar, the simplest version of the Nash bargaining game, using the replicator dynamics of Taylor and Jonker (1978). In a recent article, D'Arms et al. (1998) criticize his account and describe a model which, they allege, undermines his theory. I sketch a (...) theory of evolutionary explanations of justice which avoids their methodological criticisms, and develop a spatial model of divide-the-dollar with more robust convergence properties than the models of Skyrms (1996) and D'Arms et al. (1998). (shrink)

Decision theory faces a number of problematic gambles which challenge it to say what value an ideal rational agent should assign to the gamble, and why. Yet little attention has been devoted to the question of what an ideal rational agent is, and in what sense decision theory may be said to apply to one. I show that, given one arguably natural set of constraints on the preferences of an idealized rational agent, such an agent is forced to be indifferent (...) among entire families of goods, and hence cannot choose among them. This result illustrates the dangers of speaking of the choices of an ?ideal rational agent? when one does not make precise the exact nature of the idealizing assumptions. The result may also be viewed as providing an upper bound on the kinds of idealizing assumptions which can be made for rational agents, beyond which the very concept of choice becomes attenuated. (shrink)

The Pasadena game is an example of a decision problem which lacks an expected value, as traditionally conceived. Easwaran (2008) has shown that, if we distinguish between two different kinds of expectations, which he calls ‘strong’ and ‘weak’, the Pasadena game lacks a strong expectation but has a weak expectation. Furthermore, he argues that we should use the weak expectation as providing a measure of the value of an individual play of the Pasadena game. By considering a modified version of (...) the Pasadena game, I argue that weak expectations may provide a very poor measure of the value of an individual play of the game, and hence should not be used to value individual plays unless further information is taken into consideration. (shrink)

Assume that all algebras are atomless. (1) $Spind(A x B) = Spind(A) \cup Spind(B)$ . (2) $(\prod_{i\inI}^{w} = {\omega} \cup \bigcup_{i\inI}$ $Spind(A_{i})$ . Now suppose that $\kappa$ and $\lambda$ are infinite cardinals, with $kappa$ uncountable and regular and with $\kappa \textless \lambda$ . (3) There is an atomless Boolean algebra A such that $\mathfrak{u}(A) = \kappa$ and $i(A) = \lambda$ . (4) If $\lambda$ is also regular, then there is an atomless Boolean algebra A such that $t(A) = \mathfrak{s}(A) = (...) \kappa$ and $\mathfrak{a}(A) = \lambda$ . All results are in ZFC, and answer some problems posed in Monk [01] and Monk [ $\infty$ ]. (shrink)

Recent years have seen increased interest in the question of whether it is possible to provide an evolutionary game-theoretic explanation for certain kinds of social norms. I sketch a proof of a general representation theorem for a large class of evolutionary game-theoretic models played on a social network, in hope that this will contribute to a greater understanding of the long-term evolutionary dynamics of such models, and hence the evolution of social norms.

Whereas The Stag Hunt and the Evolution of Social Structure supplements Evolution of the Social Contract by examining some of the earlier work’s strategic problems in a local interaction setting, no equivalent supplement exists for The Dynamics of Rational Deliberation . In this article, I develop a general framework for modeling the dynamics of rational deliberation in a local interaction setting. In doing so, I show that when local interactions are permitted, three interesting phenomena occur: (a) the attracting deliberative equilibria (...) may fail to agree with any of the Nash equilibria of the underlying game, (b) deliberative dynamics which converged to the same deliberative outcome in The Dynamics of Rational Deliberation may lead to different deliberative outcomes here, and (c) Bayesian deliberation seems to be more likely to avoid nonstandard deliberative outcomes, contrary to the result reported in The Dynamics of Rational Deliberation , which argued in favour of the Brown–von Neumann–Nash dynamics. (shrink)

This book offers an original account of the good life in late modernity through a uniquely sociological lens. It considers the various ways that social and cultural factors can encourage or impede genuine efforts to live a good life by deconstructing the concepts of happiness and contentment within cultural narratives of the good life. Although empirical studies have dominated the discourse on happiness in recent decades, the emphasis on finding causal and correlational relationships has led to a field of research (...) that arguably lacks a reliable theoretical foundation. 'Deconstructing Happiness' offers a step toward developing that foundation by offering characteristically sociological perspectives on the contemporary fascination with happiness and well-being. In doing so, it seeks to understand the good life as a socially mediated experience rather than a purely personal or individually defined way of living. The outcome is a book on happiness, contentment and the good life that considers the influence of democracy, capitalism and progress while also focusing on the more theoretical challenges of self-knowledge, reason and interaction. (shrink)

Strong reciprocators possess two behavioural dispositions: they are willing to bestow bene ts on those who have bestowed bene ts, and they are willing to punish those who fail to bestow bene ts according to some social norm. There is no doubt that peoples' behaviour, in many cases, agrees with what we would expect if people are strong reciprocators, and Fehr and Henrich argue that many people are, in fact, strong reciprocators. They also suggest that strongly reciprocal behaviour may be (...) brought about by specialised cognitive architecture produced by evolution. I argue that specialised cognitive architecture can play a role in the production of strongly reciprocal behaviour only in a very attenuated sense, and that the evolutionary foundations of strong reciprocity are more likely cultural than biological. (shrink)

Cheap talk has often been thought incapable of supporting the emergence of cooperation because costless signals, easily faked, are unlikely to be reliable (Zahavi and Zahavi, 1997). I show how, in a social network model of cheap talk with reinforcement learning, cheap talk does enable the emergence of cooperation, provided that individuals also temporally discount the past. This establishes one mechanism that suffices for moving a population of initially uncooperative individuals to a state of mutually beneficial cooperation even in the (...) absence of formal institutions. (shrink)

The least element 0 of a finite meet semi-distributive lattice is a meet of meet-prime elements. We investigate conditions under which the least element of an algebraic, meet semi-distributive lattice is a (complete) meet of meet-prime elements. For example, this is true if the lattice has only countably many compact elements, or if |L| < 2ℵ0, or if L is in the variety generated by a finite meet semi-distributive lattice. We give an example of an algebraic, meet semi-distributive lattice that (...) has no meet-prime element or join-prime element. This lattice L has |L| = |LC| = 2ℵ0 where Lc is the set of compact elements of L. (shrink)

We introduce a dynamic model for evolutionary games played on a network where strategy changes are correlated according to degree of influence between players. Unlike the notion of stochastic stability, which assumes mutations are stochastically independent and identically distributed, our framework allows for the possibility that agents correlate their strategies with the strategies of those they trust, or those who have influence over them. We show that the dynamical properties of evolutionary games, where such influence neighborhoods appear, differ dramatically from (...) those where all mutations are stochastically independent, and establish some elementary convergence results relevant for the evolution of social institutions. (shrink)

In a highly influential work, List and Pettit (Group Agency: The Possibility, Design, and Status of Corporate Agents, Oxford University Press, 2011) draw upon the theory of judgement aggregation to offer an argument for the existence of nonreductive group agents; they also suggest that nonreductive group agency is a widespread phenomenon. In this paper, we argue for the following two claims. First, that the axioms they consider cannot naturally be interpreted as either descriptive characterisations or normative constraints upon group judgements, (...) in general. This makes it unclear how the List and Pettit argument is to apply to real world group behaviour. Second, by examining empirical data about how group judgements are made by a powerful international regulatory board, we show how each of the List and Pettit axioms can be violated in ways which are straightforwardly explicable at the level of the individual. This suggests that group agency may best be understood as a pluralistic phenomenon, where close inspection of the dynamics of intragroup deliberation can reveal that what prima facie appears to be a nonreductive group agent is, in fact, reducible. (shrink)

Given a model \ of set theory, and a nontrivial automorphism j of \, let \\) be the submodel of \ whose universe consists of elements m of \ such that \=x\) for every x in the transitive closure of m ). Here we study the class \ of structures of the form \\), where the ambient model \ satisfies a frugal yet robust fragment of \ known as \, and \=m\) whenever m is a finite ordinal in the sense (...) of \ Our main achievement is the calculation of the theory of \ as precisely \-\. The following theorems encapsulate our principal results:Theorem A. Every structure in \ satisfies \-\.Theorem B. Each of the following three conditions is sufficient for a countable structure \ to be in \: \ is a transitive model of \-\. \ is a recursively saturated model of \-\. \ is a model of \.Theorem C. Suppose \ is a countable recursively saturated model of \ and I is a proper initial segment of \ that is closed under exponentiation and contains \. There is a group embedding \ from \\) into \\) such that I is the longest initial segment of \ that is pointwise fixed by \ for every nontrivial \.\)In Theorem C, \\) is the group of automorphisms of the structure X, and \ is the ordered set of rationals. (shrink)

By a classical theorem of Harvey Friedman, every countable nonstandard model $\mathcal {M}$ of a sufficiently strong fragment of ZF has a proper rank-initial self-embedding j, i.e., j is a self-embedding of $\mathcal {M}$ such that $j[\mathcal {M}]\subsetneq \mathcal {M}$, and the ordinal rank of each member of $j[\mathcal {M}]$ is less than the ordinal rank of each element of $\mathcal {M}\setminus j[\mathcal {M}]$. Here, we investigate the larger family of proper initial-embeddings j of models $\mathcal {M}$ of fragments of (...) set theory, where the image of j is a transitive submodel of $\mathcal {M}$. Our results include the following three theorems. In what follows, $\mathrm {ZF}^-$ is $\mathrm {ZF}$ without the power set axiom; $\mathrm {WO}$ is the axiom stating that every set can be well-ordered; $\mathrm {WF}$ is the well-founded part of $\mathcal {M}$ ; and $\Pi ^1_\infty \text{-}\mathrm {DC}_\alpha $ is the full scheme of dependent choice of length $\alpha $.Theorem A.There is an $\omega $ -standard countable nonstandard model $\mathcal {M}$ of $\mathrm {ZF}^-+\mathrm {WO}$ that carries no initial self-embedding $j:\mathcal {M} \longrightarrow \mathcal {M}$ other than the identity embedding.Theorem B.Every countable $\omega $ -nonstandard model $\mathcal {M}$ of $\ \mathrm {ZF}$ is isomorphic to a transitive submodel of the hereditarily countable sets of its own constructible universe $L^{\mathcal {M}}$.Theorem C.The following three conditions are equivalent for a countable nonstandard model $\mathcal {M}$ of $\mathrm {ZF}^{-}+\mathrm {WO}+\forall \alpha \ \Pi ^1_\infty \text{-}\mathrm {DC}_\alpha $. There is a cardinal in $\mathcal {M}$ that is a strict upper bound for the cardinality of each member of $\mathrm {WF}$. $\mathrm {WF}$ satisfies the powerset axiom.For all $n \in \omega $ and for all $b \in M$, there exists a proper initial self-embedding $j: \mathcal {M} \longrightarrow \mathcal {M}$ such that $b \in \mathrm {rng}$ and $j[\mathcal {M}] \prec _n \mathcal {M}$. (shrink)

Basado enteramente en pruebas internas, este estudio se propone mostrar que el manuscrito único del Dīwān de Ibn Quzmān, publicado en edición facsímil por David de Gunzburg en 1896, es una copia dictada. Se indica también que el copista, a quien con frecuencia se ha culpado de introducir en el texto popular andaluz correcciones o clasicismos, no estaba bien equipado para desempeñar tal papel. Si bien era un calígrafo de primera categoría, se aducen pruebas de que su conocimiento del árabe (...) no estaba a la altura de la calidad de su caligrafía. El estudio muestra que él fue el responsable de una amplia gama de problemas textuales que ha dejado perplejos a sucesivos editores del Dīwān. En marcado contraste, se muestra que Ibn Quzmān poseía un dominio magistral de la lengua árabe y de las tradiciones-árabes clásicas. Al parecer también había adquirido un alto grado de 'aculturación' en la lengua romance. Además de ofrecer las pruebas en que se basan estos asertos, el estudio constituye un ejemplo ilustrativo de cómo estas pruebas pueden ayudar a una mejor lectura e interpretación del Dīwān de Ibn Quzmān. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:American Journal of Philology 123.3 (2002) 529-534 [Access article in PDF] Colin Adams and Ray Laurence, eds. Travel and Geography in the Roman Empire. London and New York: Routledge, 2001. x + 202 pp. 48 black-and-white figures. Cloth, $75. Five of the six contributions to this varied and valuable collection of essays originated as papers delivered at the 1999 Roman Archaeology Conference in Durham, England. The sixth and longest (...) piece, by Benet Salway, was then added, together with an introduction by one co-editor (Adams) and an afterword by the [End Page 529] other (Laurence). Notes follow each contribution, with a consolidated bibliography and index at the end. Although in black and white only, the range of photos, figures, and maps is appropriately extensive.The volume stems from due recognition that geographical knowledge and travel in the Roman world are topics at last attracting the serious attention they deserve. Between them, the contributions amply demonstrate how even some of the aspects most fundamental to our understanding stir deep controversy and how incomplete the exploitation of much of the diverse source material has been to date. Happily, the emergence of exciting new discoveries is prompting fresh examination of testimony long known and neglected.Useful, though limited in scope, is Anne Kolb's "Transport and Communication in the Roman State: The cursus publicus" (95-105), which mainly confines itself to identifying those categories of imperial officials and other individuals entitled to use the service (more properly referred to as vehiculatio during the Principate). By contrast, the support Kolb offers for the doubtful claim that transport of freight—other than baggage accompanying officials—was a "relatively unimportant" aspect of the service, even in the Late Empire (102), remains inadequate. Throughout, changes to the service over such a long span seem underappreciated (not least, for example, Nerva's removal of the burden from Italy).Adams modestly characterizes his contribution "'There and Back Again': Getting around in Roman Egypt" (138-66) as descriptive rather than analytical. His aim is to demonstrate the scope and value of the testimony preserved on papyri, and he does this engagingly, with unfailing regard for the impact of Egypt's unique geography and topography on travel there. Even though its publication dates back to 1952, few readers are likely to be familiar with the extensive archive preserving an itinerary and accounts for Theophanes' return journey from Antinoopolis to Antioch around 320 (160-62). Even fewer will be aware of the record of travelers and animals accommodated overnight, and rations issued to them, kept by the two large, busy mansiones in the Oxyrhynchite nome during the mid-fourth century and only published in 1994 (142-44). Vivid illustration of the multiple hazards awaiting travelers by road from causes both natural and human (154-56) can serve as a sobering counterbalance to the ideal conditions evoked by Aelius Aristides and quoted earlier by Adams (as eulogy) in the Introduction (1-2). One manifestation of "recreational" travel, which seems strangely absent from the discussion, on page 157 in particular, is pilgrimage (note, in general, Der Neue Pauly, s.v. Pilgerschaft 1).Jon Coulston's "Transport and Travel on the Column of Trajan" (106-37) is another predominantly descriptive contribution but one well geared to substantiate its conclusion: "The conflict is not simply between Romans and Dacians, Trajan and Decebalus. It is also a contest between Romans and barbarians, disciplina and perturbatio, labor and inertia, imperial virtues and enemy perfidy, civilisation and untamed nature, urbanisation and wilderness" (129-30). Description, moreover, is justified here when no other piece of Roman propaganda art, [End Page 530] before or after, depicts armies on the move—tents (for which soldiers were charged! [Tacitus Annals 1.17.4]), carts, pack animals, equipment, provisions, along roads, over bridges—with such amazing fullness and detail. We possess no more forceful illustration of the huge "train" that had to accompany every legion (118-19; the comparison made with Ottoman armies on campaign in the sixteenth and seventeenth centuries is instructive). Coulston's acute observation, lucid presentation, and reluctance to overinterpret... (shrink)