Game Theory and Pragmatics

Veranstaltungsbeginn 05.10.2012, 09.00 Uhr
Veranstaltungsende 06.10.2012, 18.00 Uhr
Ort ZAS

This workshop is a meeting of the European interest group in game theoretic pragmatics. It brings together leading scientists in the field, and is intended as a forum for the discussion of recent and on-going research. 

Is has long been argued that the proper understanding of language use depends on a proper understanding of the principles that govern interaction between rational agents in general. Game theory is the science of interactive decision making. As such, it is the natural foundational framework of linguistic pragmatics. Over the last decade, a firm research community has emerged with a strong interdisciplinary character, involving economists, linguists, mathematicians, philosophers, and social scientists. Within this field of research, three major currents can be distinguished: one is closely related to the Gricean paradigm and aims at a precise foundation of pragmatic reasoning, the second originates in the economic literature and is concerned with the role of game theory in the context of language use, and the third aims at language evolution seen either from a biological or cultural perspective. 

Game Theory and Pragmatics Meeting
October 5-6, 2012
ZAS Berlin

Speakers:

Abstracts

Communication, games, and errors
Anton Benz (ZAS Berlin)

Classical game theory is concerned with the interdependent decision making ofrational agents. Parameters which enter its models are the agents' informationstates, preferences, and choices of action. Models of bounded rationality, ingeneral, acknowledge cognitive parameters only in the form of weaker rationalitycriteria. In this talk we argue that cognitive processes of language production playa central role in linguistic pragmatics, in particular, in their capacity of predictingdeviations from strictly literal communication. We further argue that standardsignaling games have to be extended to allow for hearer feedback in the form ofclarification requests. If costs of communication are nominal and deviations fromliteral communication are interpreted as errors, then the existence of clarificationrequests will remove all ambiguity from communication, in particular, they will notallow interpretation by guessing. We will discuss a number of examples involvingrelevance implicatures, exhaustification, and embedded scalar implicatures.

Implicatures in discourse: some observations and ideas
Anton Benz & Katja Jasinskaja (ZAS Berlin)

In the neo-Gricean tradition quantity implicatures are generated on sentential, oreven sub-sentential level. In recent years more and more arguments have beenput forward which indicate that implicatures are, in fact, discourse phenomena.Among the most interesting examples are those discussed by Asher (2012):

(1)   If you take cheese or dessert, you pay $ 20; but if you take both there is asurcharge.

(2)   If you take only a cheese dish or only a dessert, the menu is 20 euros; butif you take both, there is a surcharge.

(3)   If John owns two cars, then the third one outside his house must be hisgirlfriend’s.

(4)   If John owns two cars only, then the third one outside his house must behis girlfriend’s.

The sentences in (1) and (3) have the implicatures in (2) and (4). However, it hasoften been argued that standard scalar implicatures do not arise in negativepolarity contexts. Asher explains that they are triggered by the discourse relationsof the conditionals. We discuss these and similar examples but argue that theycan be explained in a question based discourse theory. In particular, we willdemonstrate in detail how example (1) can be explained in the framework of errormodels as proposed in (Benz 2012).

Stating the obvious: evolutionary foundations of a fragment of conversational maxims
Stefano Demichelis (U Pavia)

We show that in repeated games or in games with previous communication evolution leads to efficient outcomes, as intuition suggests. Actions used a implicit messages or the presence of a shared meaning correspondence enable to suggest better coordination and to break symmetries when these lead to inefficiency.
For coordination games and their generalizations this characterizes evolutionary stable payoffs. Simple ”behavioral maxims” emerge in the evolutionary path, in the case of Communications these constitute a fragment of Grice's conversational maxims. Previous claims to have solved the problem and their shortcomings will be discussed, too.

Fuzzy language in action
Michael Franke (Amsterdam)

Sim-max games are signaling games with a large state space and only fewmessages where the receiver tries to guess the actual state and both players'utilities are proportional to the similarity of the actual state and the receiver'sguess. These games have been used to account for some alleged key propertiesof basic perceptual categories, such as convexity and vagueness (Jäger 2007,Jäger and van Rooij 2007, Franke et. al 2010). In this talk I explore an extensionof sim-max games in which some messages are basic predicates (think: tall orshort) while others are composite (think: tall and not tall). The meaning of atomicexpressions varies as usual with the way the expression is used. The meaning ofcomposite expressions then is derived from the variable meaning of atomicexpressions based on a fixed fuzzy logical semantics. Effectively, this extensionhelps study the influence that the availability of compositional expressions has onthe use/meaning of the underlying atomic expressions. Moreover, we obtainpredictions about the optimized use of the derived compositional expressions.Numerical simulations show that the available compositional terms push themeaning of atomic expressions to more extreme values as vindicated in empiricalstudies (e.g., Schmidt et al. 2009, Solt & Gotzner 2012), thus explaining why talldoes not denote individuals just slightly taller than average, as plain sim-maxgames would predict. We also receive clear predictions about the use of complexexpressions, including so-called borderline contradictions, such as tall and not tall,that line up well with recent experimental results (Alxatib and Pelletier 2011, Ripley2011, Serchuck et al. 2011).

Interdependencies of Production and Perception in Signaling Games
Roland Mühlenbernd (U Tübingen)

The application of signaling games (Lewis, 1969) to explain conventional language use is manifoldly examined by employing various dynamics that generate cultural evolution in a multi-agent setup (as an overview see Huttegger and Zollman, 2011). Particularly prominent in combination with repeated signaling games are the replicator dynamics (cf. Wärneryd, 1993; Huttegger, 2007), different imitation dynamics (cf. Zollman, 2005; Wagner, 2008) and learning dynamics (cf. Young, 1993; Skyrms, 2010). In contrast to the standard 'two players one shot' game here in most of the studies agents play a symmetrized game by switching between sender and receiver role. In such a scenario agents use a strategy pair (s,r) of sender strategy s and receiver strategy r. In all referable accounts known to me agents' sender role and receiver role behavior are isolated from each other. Concerning this issue I claim that it is much more plausible that agents' sender role and receiver role behavior are influenced by each other. For that purpose I define the set of plausible strategy pairs for static signaling games. Furthermore for dynamic signaling games I present a learning dynamics account that considers interdependencies of production (sender role behavior) and perception (receiver role behavior).

Quantity implicatures and signalling games. Iterated admissibility as a solution concept in game-theoretic pragmatics
Sascia Pavan (Italy)

In this talk I shall propose a game-theoretic account of quantity implicatures which models a conversation as a signalling game. It is shown that methods usually employed for signalling games in the literature are effective solution concepts in this case. Attention will be focused on iterated admissibility (a.k.a. iterated weak dominance, see Fudenberg and Tirole 1991) and elimination of type-message pairs by dominance (Cho and Kreps 1987). In some cases, this approach will presuppose an additional assumption which will be defended providing some independent empirical evidence. Some rival game-theoretic accounts of the same phenomena will be criticised. It will be argued that the theories of Prashant Parikh (1992, 2001) and Gerhard Jäger (2011) lead to incorrect empirical predictions, while Robert van Rooij's theory (2008) will be criticised from a more abstract perspective. Finally, a possible improvement of the present account will be briefly explored, namely the employment of the much stronger notion of strategic stability (Kohlberg and Mertens 1986).

About Face!
Jason Quinley (U Tübingen)

Politeness is arguably both the most strategic domain of pragmatics and the mostcounter-intuitive, as many of its strategies tend to run counter to traditionalpragmatic processes of efficient information transmission. This paper builds onrecent work in game-theoretic treatments of politeness towards two ends:connecting speech acts with game models and the notion of face with reputation.
The speech acts considered will include, but not be limited to, requests andproposals. In particular, we will discuss the use of the subjunctive mood as bothan extra strategy players can use and an expression encoding possible worldsemantics that can change the information states of the two players involved.
As for face, we will examine Brown and Levinson's (1978) notions of positive andnegative face, i.e. the preferences for autonomy and acceptance that agents haveand how they can be factored into game models in a manner similar to work doneon reputation within games like the Prisoner's Dilemma.

Modeling scalar implicatures with iterated weak dominance
Daniel Rothschild (Oxford U)

I will discuss some of the basic decision points in representing the derivation ofscalar implicatures using a game-theoretic model.  I argue that iterated weakdominance captures scalar implicature derivation in a more traditional and robustway than many other current methods.  I will also discuss the downsides of usingiterated weak dominance.

"Embedded" scalar implicature and probabilistic reasoning
Benjamin Russell (USA)

A number of studies appeared in the linguistic pragmatics literature around theturn of the millennium that questioned the traditional Gricean view of scalarimplicature.  These studies argued that, while the application of Gricean reasoningmay be straightforward for simple sentences, typical Gricean arguments do notapply when scalar terms appear in more complex sentences, particularlysentences where the scalar term is embedded below a belief operator or otherpropositional attitude.  Gricean proponents countered that these "embedded"implicatures can be derived using extra assumptions about the attitudes of agents:with respect to belief, the necessary assumption is that an agent is opinionatedwith respect to a stronger alternative (George either believes all of the studentsare missing or he believes not all are missing).  Grammatical proponentsresponded that, while an opinionatedness assumption is plausible for neg-raisingpredicates like believe, it is not plausible for non-neg-raisers, like certain.  In thistalk, I present experimental evidence that the strength of an embedded implicatureis sensitive to the likelihood of opinionatedness for the embedding predicate(which is correlated with the neg-raising property), in line with a probabilistictheory in which the strength of an embedded implicature is determined by the priorprobability distribution.

Communication in finite populations
Elliott Wagner (Amsterdam)

When a speaker’s and hearer’s interests are sufficiently misaligned,communication may not be possible at Nash equilibria.  After all, why would thereceiver listen to signals if the sender has a temptation to deceive, and why wouldthe speaker signal informatively if she can gain through exploiting the receiver’sbehavior?  Roughly speaking, this wisdom is confirmed through standard infinitepopulation models of learning and evolution in games.  Infinite population modelsdo not have limit points that are not Nash equilibria, and therefore these modelswill not lead to communication in signaling games with sufficiently misalignedinterests.  Models of finite populations, however, sometimes have radicallydifferent long-run behavior.  Due to random chance (which is washed out in infinitepopulation models), non-equilibrium strategies will occasionally become fixed infinite populations.  Using techniques developed by Fudenberg and Imhoff (2006),it is demonstrated in this paper that finite populations may have a high probabilityof sustaining communication even when the speaker’s and hearer’s interests areso divergent that separating strategies are not Nash equilibria of the underlyingsignaling game.