Publications
Books
The Open Society as an Enemy.
LSE Press (forthcoming 2024).
Description:
I argue that the concept of the Open Society, once seen as a largely unconditional good during the period
of the Cold War, has undergone a curious “inversion of values” in contemporary public discourse. In this book,
I examine four aspects of the open society and their interrelations: open borders and free movement of people,
informational transparency and privacy, free exchange of ideas, and polarization and tribalism in modern society.
A central thesis is that aspects now framed as "good" in public discourse, such as informational transparency,
often curtail individual freedoms by increasing the power of organizations or governments.
Conversely, aspects now framed as "bad," such as open borders, could enhance individual freedoms if appropriately enacted.
However, I qualify this claim, acknowledging that some aspects of the Open Society can be developed to mitigate the
identified threats, and that reasonable people may disagree on the extent to which certain aspects constitute a threat or
provide a benefit.
The book aims to rehabilitate the concept of the Open Society, helping readers appreciate which aspects are worth
preserving and which need to be curtailed to support human freedoms, personal autonomy, and create a
society worth living in.
Evolutionary Game Theory.
Cambridge University Press (2023).
Description: Evolutionary game theory originated in population biology from the realisation
that frequency-dependent fitness introduced a strategic element into evolution. Since its development,
evolutionary game theory has been adopted by many social scientists, and philosophers, to analyse
interdependent decision problems played by boundedly rational individuals. Its study has led to
theoretical innovations of great interest for the biological and social sciences.
For example, theorists have developed a number of dynamical models which can be used to study how
populations of interacting individuals change their behaviours over time. In this introduction, this
Element covers the two main approaches to evolutionary game theory: the static analysis of evolutionary
stability concepts, and the study of dynamical models, their convergence behaviour and rest points.
This Element also explores the many fascinating, and complex, connections between the two approaches.
The Structural Evolution of Morality.
Cambridge University Press (2007).
Description: 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 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.
Stanford Encyclopedia of Philosophy
Book Chapters
“Evolutionary Game Theory,” in
The Handbook of Rationality,
edited by Markus Knauff and Wolfgang Spohn, The MIT Press (December 2021).
“Evolutionary Game Theory,” in The New Handbook of Mathematical Psychology, Volume 1: Measurement and Methodology, edited by William Batchelder, Hans Colonius,
Ehtibar Dzhafarov and Jay Myung, ch. 6, pp. 322-373, Cambridge University Press (December 2016).
“Co-operation,”
in
A Companion to the Philosophy of Biology.
Eds. Sahotra Sarkar and Anya Plutynski. Blackwell Publishers (March 2008).
“Game Theory,”
in The Philosophy of Science: An Encyclopedia,
vol. 1. Ed. Sahotra Sarkar. Routledge Press (2005): 323–329.
“Artificial Justice,”
in Artificial Life VIII.
Eds. Mark A. Bedau, John S. McCaskill, Norman H. Packard, and Steen Rasmussen. MIT Press (2000): 513–523.
Edited Volumes
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Proceedings of the Philosophy of Science Association Twentieth Biennial
Meeting (with Cristina Bicchieri) U of Chicago P, vols. I and II (2007, 2008).
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Proceedings of the Philosophy of Science Association Seventeenth Biennial
Meeting (with Jeffrey Barrett) U of Chicago P, (2001, 2002).
Journal Articles
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“On the Incompleteness of Classical Mechanics,”
The British Journal for the Philosophy of Science,
forthcoming (accepted May 2024).
Abstract
Classical mechanics is often considered to be a quintessential example of a deterministic theory.
I present a simple proof, using a construction mathematically analogous to that of the Pasadena
game (Nover and Hájek [2004]), to show that classical mechanics is incomplete: there are
uncountably many arrangements of objects in an infinite Newtonian space such that, although
the system’s initial condition is fully known, it is impossible to calculate the system’s future
trajectory because the total force exerted upon some objects is mathematically undefined.
It is then shown how variations of this discrete system can be obtained which increasingly
approximate a uniform mass distribution, similar to that underlying a related result, due to
von Seeliger ([1895]). It is then argued that this incompleteness result, as well as that
presented by the Pasadena game, has no real philosophical significance as it is a mathematical
pseudoproblem shared by all models which attempt to aggregate infinitely many numerical
values of a certain kind.
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“A Model of the Dynamics of Subgroup Influence on Boards,”
(co-authored with Julia Morley), Academy of Management Proceedings,
vol. 2022, issue 1 (2022).
Abstract
Before making a decision, it is common for groups to deliberate. It is often thought
that deliberation improves the resulting group decision by pooling individual information,
enabling group members to participate, and ensuring all views are expressed and
taken into consideration. However, recent work on group decision-making in organisations
has highlighted potential negative effects of deliberation which result from compositional
issues (e.g., “faultlines”). In this paper, we identify another means by which group
deliberation can go awry, showing how the dynamics of deliberation itself can allow
small subgroups to wield undue influence on the final decision, a phenomenon we
label “deliberational capture”. Deliberational capture occurs when the process of
group deliberation enables a subgroup to repeatedly trigger individual cognitive
biases as a result of the deliberational style of subgroup members rather than the
propositional content of their arguments. This result matters because it is frequently
assumed that controlling for group composition and basic procedural matters, such as
access to information, suffice for effective group decision-making. In contrast, we argue
that the phenomenon of deliberational capture shows that the dynamics of deliberation deserve greater attention.
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"Accounting for Groups: The Dynamics of Intragroup Deliberation,"
(co-authored with Julia Morley), Synthese, vol. 199,
no 3-4, pp. 7957-7980 (2021).
Abstract
In a highly influential work, List and Pettit (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.
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"Cheap Talk, Reinforcement Learning and the Emergence of Cooperation,"
Philosophy of Science, vol. 82, no. 5, pp. 969–982 (December 2015).
Abstract
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.
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"Epistemic landscapes, Optimal Search and the Division of Cognitive Labor,"
(co-authored with Johannes Himmelreich and Chris Thompson),
Philosophy of Science, vol. 82, no. 3, pp. 424–453 (July 2015).
Abstract
This article 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, “Epistemic Landscapes and the
Division of Cognitive Labor”, 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.
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“Learning to Signal in a Dynamic World,”
The British Journal for the Philosophy of Science, vol. 65, pp. 797–820 (2014).
Abstract
Sender-receiver games, first introduced by David Lewis in Convention,
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,
Skyrms et al. (2011) showed that reinforcement learning, combined with
forgetting, frequently produced both efficient and minimal signalling systems.
In this paper 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.
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“Preferential Attachment and the Search for Successful Theories,”
Philosophy of Science, vol. 80, pp. 769–782 (December 2013).
Abstract
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.
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“On the Redress of Grievances,”
Analysis, vol. 73, no. 2, pp. 228–230 (April 2013).
Abstract
Consider the problem of allocating a scarce resource to people. A fair decision
procedure is one where each person has an equal chance of receiving the resource. An
unfair decision procedure is one where the chances vary. For simplicity, let's
restrict attention to
the case where there are only two people involved. Call the person with the higher
probability of receiving the resource the favoured and the person with the lower
chance of receiving the resource the aggrieved. Normally we think that, in an
unfair decision procedure, that the correct way to redress the injustice is by rerunning
the allocation using a fair decision procedure. In this paper, I show that this actually
creates an overall bias for the aggrieved. And solutions to this problem are
counterintuitive, in that they typically involve introducing additional unfair elements
into the situation. So, in this case, two wrongs do make a right.
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“Why the Angels Cannot Choose,”
The Australasian Journal of Philosophy, vol. 90, no. 4, pp. 619–640 (December 2012).
Abstract
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 idealised 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 idealising assumptions. It may
also be viewed as providing an upper bound on the kinds of idealising assumptions which
can be made for rational agents, beyond which the very concept of choice becomes less
applicable.
Keywords: Decision theory · game theory · choice
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“Decision Theory meets the Witch of Agnesi,”
The Journal of Philosophy, vol. CIX, no. 12, pp. 712–727 (December 2012).
Abstract
Decision theory offers the following rule for how rational agents ought to
choose: take whatever action serves to maximise your expected utility. Although
it is generally recognised that choice under uncertainty may generate cases
where the agent cannot maximise her expected utility, it is typically thought
that rational agents can maximise their expected utility if they have
full knowledge of the outcomes and full knowledge of the probability
distribution over outcomes. In this paper I construct a gamble which satisfies
these last two conditions but, nevertheless, a rational agent cannot assign a
value to the gamble (even though it is clearly in the interest of the rational
agent to participate) because no expected value exists. This gamble differs
from the St. Petersburg paradox in that it involves both positive and negative
payoffs, and it differs from the Pasadena game in that the method of weak
expectations does not work.
Keywords: Decision theory · weak expectations · Cauchy distribution
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“Inventing New Signals,”
(co-authored with Brian Skyrms and Sandy Zabell),
Dynamic Games and Applications, vol. 2, issue 1, pp. 125–145 (March 2012).
[An online version of the simulation discussed in that paper
is available.]
Abstract
A model for inventing new signals is introduced in the context of sender–receiver
games with reinforcement learning. If the invention parameter is set to zero, it
reduces to basic Roth–Erev learning applied to acts rather than strategies, as in
Argiento et al. (Stoch. Process. Appl. 119:373–390, 2009). If every act is uniformly
reinforced in every state it reduces to the Chinese Restaurant Process—also known as
the Hoppe-Pólya urn—applied to each act. The dynamics can move players from one
signaling game to another during the learning process. Invention helps agents avoid
pooling and partial pooling equilibria.
Keywords: Signals · Invention · Reinforcement · Chinese Restaurant
Process · Hoppe–Pólya urn
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“Expectations and Choiceworthiness,”
Mind, vol. 120, no. 479, pp. 803–817 (2011).
Abstract
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.
Keywords: Pasadena game · weak expectations
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“Local Interactions and the Dynamics of Rational Deliberation,”
Philosophical Studies, vol. 147, pp. 102–121 (2010).
Abstract
Whereas
The Stag Hunt and the Evolution of Social Structure
supplements
Evolution of the Social Contract by revisiting
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 very
different deliberative outcomes, 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.
Keywords: Evolution · Rationality · Bayesianism · Brown-von
Neumann-Nash dynamics · Social Network
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“Robustness, Optimality, and the Handicap Principle,”
Biology and Philosophy, vol. 25, pp. 868–879 (2010).
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“Social Deliberation: Nash, Bayes, and the Partial Vindication of Gabriele Tarde,”
Episteme, 6(2): 164–184 (2009).
Abstract
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.
Keywords: Gabriele Tarde · Evolutionary game theory · Centipede game ·
Nash-Brown-von Neumann dynamics
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“Book Review: The Stag Hunt and the Evolution of Social Structure.”
Economics and Philosophy, 22 (2006): 441–448.
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“The Evolutionary Foundations of Human Altruism,”
Analyse & Kritik, vol. 27, pp. 106–113 (2005).
Abstract
Strong reciprocators possess two behavioural dispositions: they are
willing to bestow benefits on those who have bestowed benefits, and
they are willing to punish those who fail to bestow benefits according
to some social norm. There is no doubt that people’s behaviour,
in many cases, agrees with what we would expect if people are strong
reciprocators, and Fehr and Henrich (2003) 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.
Keywords: Strong reciprocity · Cultural evolution
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“Follow the Leader: Local Interactions with Influence Neighborhoods,”
(co-authored with Peter Vanderschraaf)
Philosophy of Science, pp. 86–113, (2005).
Abstract
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 (Foster
and Young, 1990), 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.
Keywords: Stag hunt · Influence neighborhood · Cultural evolution
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“Random Boolean Networks and Evolutionary Games,”
Philosophy of Science, vol. 70, pp. 1289–1304 (2003).
Abstract
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.
Keywords: Random boolean networks · Evolutionary game theory
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“Group Dynamics in the State of Nature,”
Erkenntnis 55.2 (2001): 169–182.
Abstract
One common interpretation of the Hobbesian state of nature views it
as a social dilemma, a natural extension of the well-known prisoner’s
dilemma to a group context. Kavka (1986) challenges this interpretation,
suggesting that the appropriate way to view the state of nature is
as a quasi social dilemma. I argue that Hobbes’s remarks on the rationality
of keeping covenants in the state of nature indicate that the quasi social
dilemma does not accurately represent the state of nature. One possible
solution, I suggest, views the state of nature as a social dilemma between
groups rather than individuals. Although this cleanly represents the
strategic problem faced in the state of nature, it also means we should
take intergroup dynamics into account when putting forth a solution.
I argue that Hobbes’s solution of commonwealth by institution – the favored
solution for Hobbesian social contract theories – will not work in the
state of nature viewed this way.
Keywords: State of nature · Social identity theory · in/out group
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“Evolutionary Explanations of Distributive Justice,”
Philosophy of Science, vol. 67, pp. 490–516, (2000).
Abstract
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).
Keywords: Local interaction model · Nash bargaining game · Evolution
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“Ruling Out (160,54,18) Difference Sets in Some Nonabelian Groups,”
(co-authored with Rajalakshmi Balasubramanian, Jeremy Martin, Kimberley Monahan,
Harriet Pollatsek and Ashna Sen)
Journal of Combinatorial Designs vol. 8, no. 4, pp. 221–231, (2000).
Abstract
We prove the following theorems:
Theorem A: Let G be a group of order 160 satisfying one of the
following conditions. (1) G has an image isomorphic to D20 ×
Z2 (for example, if G ≅ D20 × K). (2) G has a normal
5-Sylow subgroup and an elementary abelian 2-Sylow subgroup. (3) G has an abelian
image of exponent 2, 4, 5, or 10 and order greater than 20. Then G cannot contain
a (160, 54, 18) difference set.
Theorem B: Suppose G is a nonabelian group with 2-Sylow subgroup S and
5-Sylow subgroup T and contains a (160, 54, 18) difference set. Then we have one of three
possibilities. (1) T is normal, |φ(S)| = 8, and one of the following is
true: (a) G = S × T and S is nonabelian; (b) G has a D10
image; or (c) G has a Frobenius image of order 20. (2) G has a Frobenius image of
order 80. (3) G is of index 6 in AΓL(1,16).
To prove the first case of Theorem A, we find the possible distribution of a putative difference
set with the stipulated parameters among
the cosets of a normal subgroup using irreducible representations of the quotient; we show that no
such distribution is possible. The other two cases are due to others. In the second (due to Pott)
irreducible representations of the elementary abelian quotient of order 32 give a contradiction.
In the third (due to an anonymous referee), the contradiction derives from a theorem of Lander
together with Dillon’s “dihedral trick.” Theorem B summarizes the open nonabelian cases based on
this work.
Keywords: Difference set · finite group · Symmetric design
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“Bargaining with Neighbors: Is Justice Contagious?”
(co-authored with Brian Skyrms) Journal of Philosophy 96.11 (1999): 588–598.
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