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DISCIPLINE FILOSOFICHE Anno XXV, Numero 1, 2015 DISCIPLINE FILOSOFICHE Anno XXV, numero 1, 2015 Quodlibet DISCIPLINE FILOSOFICHE Anno XXV, numero 1, 2015 Rivista fondata da Enzo Melandri. Periodicità semestrale. Dipartimento di Filosofia e Aut. Tribunale di Macerata, n. 527/ Comunicazione stampa del 16. 12. 2005 ISSN: 1591-9625 Direttore Stefano Besoli Direttore responsabile Barnaba Maj Comitato scientifico Massimo Barale (Università di Pisa) †, Jocelyn Benoist (Université Paris-I Panthéon- Sorbonne), Giuseppe Cantillo (Università Federico II di Napoli), Jean-François Courtine (Université Paris-IV Sorbonne), Françoise Dastur (Université de Nice Sophia Antipolis), Roberta De Monticelli (Università Vita-Salute San Raffaele di Milano), Bianca Maria d’Ippolito (Università di Salerno) †, Massimo Ferrari (Università di Torino), Gottfried Gabriel (Friedrich Schiller Universität Jena), Gianna Gigliotti (Università Tor Vergata di Roma), Wolfhart Henckmann (Ludwig-Maximilians-Universität München), Douglas Hofstadter (Indiana University), John Lachs (Vanderbilt University), Claudio La Rocca (Università di Genova), Eugenio Mazzarella (Università Federico II di Napoli), Ernst Wolfgang Orth (Universität Trier), Renato Pettoello (Università di Milano), Manfred Sommer (Christian-Albrechts-Universität Kiel), Jürgen Stolzenberg (Martin-Luther- Universität Halle-Wittenberg), Francesco Saverio Trincia (Università La Sapienza di Roma), Frédéric Worms (École normale supérieure – ENS , Paris) Comitato di redazione Simona Bertolini, Francesco Bianchini, Roberto Brigati, Vincenzo Costa, Roberto Frega, Sebastiano Galanti Grollo, Michele Gardini, Alberto Gualandi, Luca Guidetti, Barnaba Maj, Giuliana Mancuso, Marina Manotta, Emanuele Mariani, Riccardo Martinelli, Maurizio Matteuzzi, Giovanni Matteucci, Venanzio Raspa, Alessandro Salice, Luca Vanzago, Giorgio Volpe Direzione e redazione Dipartimento di Filosofia e Comunicazione, via Zamboni 38 - 40126 Bologna. Tel 051-2098344. Fax 051-2098355 E-mail Redazione: [email protected] Sito web: www.disciplinefilosofiche.it Copertina: Augusto Wirbel © Copyright 2015 Quodlibet ISBN: 9788874627998 Quodlibet edizioni, via Santa Maria della Porta, 43, 62100 Macerata tel. 0733-264965 fax 0733-267358 www.quodlibet.it; e-mail: [email protected] Finito di stampare nel mese di novembre 2015 dalla Grafica Editrice Romana s.r.l., Roma. Questa Rivista è stata pubblicata con un contributo di fondi R.F.O. dell’Ateneo di Bologna. I saggi che compaiono in questa rivista sono sottoposti a double-blind peer-review. Francesca Ervas, Elisabetta Gola, Antonio Ledda and Giuseppe Sergioli Lexical Ambiguity in Elementary Inferences: an Experimental Study Abstract In this paper we discuss how common meaning ambiguities (homonymy, poly- semy and metaphors) influence the understanding of an elementary argument. In order to understand how, and to what extent, participants’ intuitions on the strength of a syllogism are influenced by meaning ambiguities, we present the results of a pilot study. The study specifically focuses on a fallacy of lexical ambiguity, where the meanings of the middle term diverge in the two premises. We hypothe- size that the evaluation of the strength of an argument of this sort is related to the nature of the ambiguity of its middle term and to the pragmatic process required to disambiguate the ambiguous meanings. We expect the persuasiveness of the syllo- gism to be directly proportional to the degree of semantic superposition of the meanings of the middle term. Keywords : Metaphor, Quaternio terminorum, Lexical ambiguity, Argumenta- tion. 1. Introduction In the informal logic tradition, fallacies are common errors of reasoning (Sergioli 2015). As it has been pointed out, “studies of fallacies in argumen- tation and informal logic have mainly taken a normative approach, by see- ing fallacies as arguments that violate standards of how an argument should properly be used in rational thinking or arguing. However, fallacies also have a psychological dimension ” (Walton 2010, p. 159, our italics). In this perspective, fallacies are arguments that seem valid but are not (Hamblin 1970). In Max Black’s Critical Thinking , the definition of fallacy is tuned up: “A fallacy is an argument that seems to be sound without being so in fact. An argument is ‘sound’ for the purpose of this definition if the conclu- sion is reached by a reliable method and the premises are known to be true” (Black 1946, pp. 129-130, our italics). However little is said in a man- ner of explanation regarding the how and why of “seeming valid” or “seem- ing sound” (Hansen 2002). Introducing lexical fallacies, Cohen and Nagel suggested that “these all seem to conform to valid forms of inference, but on careful examination are seen not to do so the appearance being due to 150 FRANCESCA ERVAS , ELISABETTA GOLA , ANTONIO LEDDA AND GIUSEPPE SERGIOLI an ambiguity, that is, to the use of the same word or verbal sign for two dif- ferent terms” (1934, p. 376). In classical argumentation theory, metaphors usually lead to fallacies of reasoning (Sergioli and Ternullo 2014; Tindale 2006), by exacerbating problems of ambiguity (Barnden 2012; Camp 2006; Fischer 2015). A sen- tence where a metaphor occurs is literally false.1 However, the context of its usage might create a perception that it is true, or at least plausible. From a literal point of view a metaphor is false, but from a non-literal point of view it may appear plausible. Fischer (2015) argues that a range of varied disci- plines have demonstrated the productive usage of metaphors in deductive reasoning: physics (Hesse 1996), biology (Keller 1995), psychology (Gentner and Grudin 1985) and problem solving (Keefer et al. 2014; Thibodeau and Boroditsky 2011). At the same time, metaphors are gov- erned by heuristic rules that never guarantee the preservation of truth, thus giving rise to systematic fallacies (Fischer 2011, 2014). This might be the reason why metaphors are highly persuasive by nature. Thus, the persua- siveness of an argument would eventually be influenced by the presence of metaphors. Following this intuition, we aim to understand the effect of metaphors in arguments with the structure of a quaternio terminorum, sometimes re- ferred to as four term fallacy , where the nature of the middle term plays a fundamental role and might influence its persuasive strength. Quaternio terminorum relies on the intrinsic ambiguity of the middle term, which is used in the premises with two different meanings. The middle term can be ambiguous either because the term has two different literal meanings (the case of homonymy and polysemy ), or because it has both a literal and a non- literal meaning (the case of lexicalized metaphor and live metaphor ). We claim that the persuasiveness of an argument varies as the ambiguity of the middle term moves through such a spectrum. In order to test our claim on a real representative sample, we set up an experimental design. Usually, argumentation theory does not employ an experimental approach and relies on a priori notions, according to which figurative language renders premises literally false and the overall argument unsound. However, an experimental approach may tell us something more about argumentation in common language and the divergences between speakers’ and scholars’ intuitions on the strength of arguments – in particu- 1 In this paper we will be exclusively concerned with literally false metaphors. However, it should be observed that there are cases of twice-true (Cohen 1976, p. 254) and twice-apt (Hills 1997, p. 130) metaphors, such as “No man is an island” and “George Bush is a primate”. See Camp (2008) for an extensive discussion. LEXICAL AMBIGUITY IN ELEMENTARY INFERENCES 151 lar, on the reason why a fallacious argument may appear strong, even if it is not. More specifically, the results of this study indicate a consistency be- tween the psychological and the normative aspects (Walton 2010; Tversky and Kahneman 1974) of quaternio terminorum. The semantic intuitions leading to the disambiguation of the middle terms allow participants to cor- rectly evaluate the arguments. This is so with participants bearing no specif- ic training in logic nor in argumentation theory. Interestingly, this con- sistency seems to weaken in case of metaphors as middle terms. This is per- haps due to the fact that the presence of metaphors renders natural lan- guage ambiguous. The structure of the paper is the following. In the first section we pro- vide the basic notions required to define quaternio terminorum and clarify the different pragmatic phenomena involved in the gamut of lexical ambi- guities. In the second section we present the experimental design of a pilot study that aims to understand whether, and to what extent, lexical ambigui- ty influences the persuasiveness of a quaternio terminorum. In the third section we present the methodology of the experimental study and describe the participants involved, either in the norming or the pilot study, the mate- rials that were presented to them and the procedure that was followed. In the fourth section we present the results of the experimental study. Finally, in the fifth section we discuss the results in the light of the aims of the over- all paper. 1.1. Basic notions In order to keep the paper self-contained, we introduce in this section all the required basic notions from argumentation theory and lexical prag- matics. 1.1.1. Argumentation theory A sentence is a declarative statement to which a truth-value (true or false), in classical logic, can be assigned
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