Razonamiento Con Condicionales Contrafacticos 'a Menos que' (Seccion EXPERIMENTAL‪)‬

The psychology of conditional reasoning has mainly centered on the study of indicative conditionals of the form 'if A then B' (Evans, Newstead, & Byrne, 1993). Our aim in this paper is not to study standard indicative 'if then' conditionals, but rather two particular kinds of conditionals: subjunctive counterfactuals and 'unless' formulations. 'Unless' is a negative conditional connective that, according to philosophers, is semantically equivalent to 'if not' (e.g., Quine, 1972; Reichenbach, 1947). An 'unless' expression such as 'Virginia will not pass the exam unless she works harder' is therefore supposedly equivalent to 'If Virginia does not work harder she will not pass the exam'. However, linguists and psycholinguists have often disagreed with this opinion. According to Fillenbaum (1986), an important part of the 'unless' expression, the stress on the need to 'work harder', is lost in the 'if not' expression. Fillenbaum (1986) has claimed that 'unless' is more closely related to 'only if' than to 'if not'. The illocutionary force of the 'unless' expression is sustained better by using an 'only if' formulation, such as 'Virginia will pass the exam only if she works harder'. People often generate counterfactuals to express what might have been different in the past (Kahneman & Tversky, 1982). Counterfactual thoughts may play an important role in cognition, emotion, and social judgements (see Byrne, 2005). For example, suppose a friend just took an important exam. After leaming the result of the exam, you might make a conjecture such as 'If Virginia had not worked hard she would not have passed the exam'. Counterfactual thoughts can be expressed in other ways, too. For example, you might have thought instead, 'Virginia would not have passed the exam unless she had worked hard', or even, 'Virginia would have passed the exam only if she had worked hard'. The 'if', 'unless' and 'only if counterfactuals seem to emphasize different aspects of the causal sequence of events. However, unless counterfactuals have not been studied yet. Our aim is to compare counterfactual conditionals based on 'unless' to ones based on 'if not' and 'only if'. We wish to examine whether people think differently about counterfactuals based on these three conditional expressions, and whether they make different inferences from them.