Arash Eshghi* and Oliver Lemon Grammars as Mechanisms for Interaction: The Emergence of Language Games DOI 10.1515/tl-2017-0010 1 Introduction In their article “Language as Mechanisms for Interaction” Kempson et al. have provided the research community with numerous real examples of complex dialogue phenomena – in particular various examples of split utterances. From the point of view of developers of real-world spoken dialogue systems (one of the perspectives that we will take in this commentary), this paper presents both a treasure-trove of examples for developers, and an important set of challenges for current work on implementing truly natural conversational interfaces. This paper is therefore of great value to developers of dialogue systems and conversational agents, in that it presents both some very challenging real data and a sustained argument for new ways of conceptualizing the traditional syntax/ semantics/pragmatics interfaces, which have dominated traditional computational linguistics. In this commentary, we hope to draw out some of the implications of the data and the arguments, and to explain some new research directions which are now underway in order to meet the various challenges that the paper presents. It is uncontentious that dialogue, the most common and natural setting for language acquisition and use, is highly fragmentary, full of interruptions, role changes, restarts, corrections, continuations and overlaps, without any of these necessarily respecting the boundaries of the sentence. Until the pioneering work of Ginzburg and Cooper (2004); Ginzburg (2012); Poesio and Rieser (2010) and few others, and indeed that of the authors of this fine work, this data had been largely ignored by traditional linguistics as instances of defective performance, relative to an abstract model of the ideal, competent speaker. This dialogue data has been notoriously difficult to capture within mainstream models of the syntax-semantics interface, as the authors of the target article (henceforth, Kempson et al.) themselves forcefully argue. This is further evidenced by the *Corresponding author: Arash Eshghi, School of Mathematical and Computer Sciences, Heriot-Watt University, Earl Mountbatten Building, Edinburgh EH14 4AS, UK, E-mail: a.eshghi@hw.ac.uk Oliver Lemon, School of Mathematical and Computer Sciences, Heriot-Watt University, Earl Mountbatten Building, Edinburgh EH14 4AS, UK, E-mail: o.lemon@hw.ac.uk Theoretical Linguistics 2017; 43(1-2): 129–133