This introductory course will present the main lines of empirical research on the psychology of reasoning of the last decades, by focusing on the points of contact with concepts and themes currently prominent in logic, and by making use of logical tools to clarify the psychological results and discussions. The main topics covered are: reasoning with conditionals, syllogistic reasoning, monotonic vs. non-monotonic reasoning. After attending the course, participants will be familiar with the main themes and empirical results on human reasoning, as investigated by experimental psychologists. It presupposes no more than basic knowledge of propositional logic, syllogistic, and the model-theoretic definition of logical consequence: as such, it is accessible to a wide audience, and requires no previous knowledge of research in psychology.

An often repeated slogan is that logic is the science of correct reasoning. But how does logic in fact relate to human reasoning? Does logic, or particular logical systems, offer an accurate descriptive account of how humans reason? Or is logic supposed to have a prescriptive import for human reasoning? These are some of the most fundamental philosophical questions pertaining to logic. Now, since the 1960s, experimental psychologists have been conducting extensive empirical studies of how human agents reason, and it seems clear that logicians and philosophers of logic have much to benefit from familiarity with this body of literature. After all, the phenomena being analyzed are very much the same: arguments, inferences, the concept of validity etc. And yet, contacts between psychologists, on the one hand, and logicians and philosophers, on the other hand, have been scarce.

One of the main themes having emerged from research on the psychology of reasoning of the last decades is the marked discrepancy between participants’ performances in reasoning tasks during the experiments and the normative responses to these tasks, as determined by the canons of traditional (deductive) logic (Evans 2002). These deviances from the ‘norm’ are conceptualized in terms of the concept of ‘reasoning biases’, which are systematic reasoning tendencies such as e.g. to take into account the believability of the conclusion to evaluate the correctness of an argument. These results have important implications both for logicians and for philosophers: what is (classical) logic about, if it (arguably) does not describe how people in fact reason? And given these results, in what sense is logic prescriptive for reasoning? Is it possible to develop logical systems which would provide a more accurate picture of human reasoning?

The proposed course, intended as an introductory course, will present the main lines of research in the psychology of reasoning since the 1960s by focusing on the points of contact with some concepts and themes currently prominent in logic and philosophy, and making use of logical tools to clarify the psychological results and discussions. After attending the course, participants will be familiar with the main themes and empirical results on human reasoning.

The course will cover the main lines of investigation in the psychology of reasoning of the last decades: reasoning with conditionals, in particular variations of the famous Wason selection task (Evans 2002; Stenning and van Lambalgen 2008; Counihan 2008); syllogistic reasoning, in particular the studies on some so-called reasoning biases such as belief bias and matching bias (Evans 2002; Dutilh Novaes 2013; Counihan 2008); reasoning with abstract or contentual material (Dutilh Novaes 2013); defeasible vs. indefeasible reasoning, and the related concepts of non-monotonicity and monotonicity (Stenning and van Lambalgen 2008; Dutilh Novaes 2013).

Session 1
Historical and philosophical introduction to the relations between logic, argumentation, reasoning, thinking, human cognition and rationality.

Session 2
Reasoning with conditionals: the many different variations of the Wason selection task, descriptive vs. deontic conditionals, matching bias, the suppression task, conditionals as defeasible.

Session 3
Syllogistic reasoning: the effects of believability on the evaluation and production of arguments, a conceptualization of belief bias in terms of non-monotonicity.

 

Bibliography:

M. Counihan 2008, Looking for logic in all the wrong places. University of Amsterdam, PhD dissertation.

C. Dutilh Novaes 2013, Formal Languages in Logic: a Philosophical and Cognitive Analysis. Cambridge, Cambridge University Press (especially chapters 4 and 7.2). Preliminary draft available here.

J.St.B.T. Evans 2002, ‘Logic and human reasoning: an assessment of the deduction paradigm’. Psychological Bulletin, 128(6), pp. 978-996.

K. Stenning & M. van Lambalgen 2008, Human reasoning and cognitive science. Cambridge MA, MIT Press.