Necessity and contingency in reasoning (original) (raw)
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laboratory of experimental Psychology, University of leuven, Belgium rationality, reasoning, conditionals, truth two experiments (N 1 = 117 and N 2 = 245) on reasoning with knowledge-rich conditionals showed a main effect of logical validity, which was due to the negative effect of counter-examples being smaller for valid than for invalid arguments. these findings support the thesis that some people tend to inhibit background inconsistent with the hypothetical truth of the premises, while others tend to abandon the implicit truth-assumption when they have factual evidence to the contrary. Findings show that adhering to the truth-assumption in the face of conflicting evidence to the contrary requires an investment of time and effort which people with a higher general aptitude are more likely to do.
In search of counterexamples: Test procedures, validity and deductive rationality in human reasoning
Two studies are presented in which reasoners were explicitly asked to test/validate conditional inferences. The results of both experiments show, first, that people are more likely to look for an alternative, a falsification (as compared to a confirmation) of the inferences. Second, falsification rates are generally lower for the logically valid (vs. invalid) inferences. Third, confirmation-rates are generally higher for denial inferences. Deductively valid inferences are inferences that follow necessarily and not just possibly. Experiment 1 (N = 96) showed that increasing the impetus on this logicality constraint increases the tendency to look for falsifications. Experiment 1confirmed that people who test an inference by searching for an alternative are more likely to make a logically correct evaluation of these inferences. Experiment 2 confirmed, the other way round, that those people who are more likely to reject the logical fallacies are more likely to test their inferences by searching for an alternatives. The results are presented and discussed in relation to contemporary theories of human reasoning.
We asked people to validate conditional inferences (e.g., "A, therefore C" with "if A then C"). People are more likely to look for falsifications ("A and not-C") versus confirmations ("A and C") given a forced choice. Second, falsification rates are lower for logically valid versus invalid inferences. Logically valid inferences are inferences that follow necessarily. Experiment 1 (N ϭ 96) shows that emphasising this logicality constraint increases falsification rates in the validation task and corroborates that validationby-falsification increases logically correct inference evaluations. Experiment 2 (N ϭ 41) corroborates the other way round that people who are more likely to make logically correct evaluations, show higher falsification performance in the validation task. The results support mental-models theory and suggest alternative theories similarly need to specify how people would go about looking for counterexamples. We proffer such a specification for two alternatives to the model theory.
Falsification or Confirmation: From Logic to Psychology
arXiv: History and Philosophy of Physics, 2015
Corroboration or confirmation is a prominent philosophical debate of the 20th century. Many philosophers have been involved in this debate most notably the proponents of confirmation led by Hempel and its most powerful criticism by the falsificationists led by Popper. In both cases however the debates were primarily based on the arguments from logic. In this paper we review these debates and suggest that a different perspective on falsification versus confirmation can be taken by grounding arguments in cognitive psychology.
The modulation of conditional assertions and its effects on reasoning
The Quarterly Journal of Experimental Psychology, 2010
The theory of mental models postulates that conditionals of the sort, if A then C, have a "core" meaning referring to three possibilities: A and C, not-A and C, and not-A and not-C. The meaning of a conditional's clauses and general knowledge can modulate this meaning, blocking certain possibilities or adding relations between the clauses. Four experiments investigated such interpretations in factual and deontic domains. In Experiment 1, the participants constructed instances of what was possible and what was impossible according to various conditionals. The results corroborated the general predictions of the model theory and also the occurrence of modulation. The resulting interpretations governed the conclusions that participants accepted in Experiment 2, which also yielded the predicted effects of a time limit on responding. In Experiment 3, the participants drew the predicted conclusions for themselves. In Experiment 4, modulation led to predicted temporal relations between A and C. We relate these results to current theories of conditionals.
New Paradigms in the Psychology of Reasoning
Annual Review of Psychology
The psychology of verbal reasoning initially compared performance with classical logic. In the last 25 years, a new paradigm has arisen, which focuses on knowledge-rich reasoning for communication and persuasion and is typically modeled using Bayesian probability theory rather than logic. This paradigm provides a new perspective on argumentation, explaining the rational persuasiveness of arguments that are logical fallacies. It also helps explain how and why people stray from logic when given deductive reasoning tasks. What appear to be erroneous responses, when compared against logic, often turn out to be rationally justified when seen in the richer rational framework of the new paradigm. Moreover, the same approach extends naturally to inductive reasoning tasks, in which people extrapolate beyond the data they are given and logic does not readily apply. We outline links between social and individual reasoning and set recent developments in the psychology of reasoning in the wider ...
Reasoning About Necessity and Possibility: A Test of the Mental Model Theory of Deduction* 1
Journal of Experimental …, 1999
This article examined syllogistic reasoning that differs from previous research in 2 significant ways: (a) Participants were asked to decide whether conclusions were possible as well as necessary, and (b) every possible combination of syllogistic premises and conclusions was presented for evaluation with both single-premise (Experiment 1) and double-premise (Experiment 2) problems. Participants more frequently endorsed conclusions as possible than as necessary, and differences in response to the 2 forms of instruction conformed to several predictions derived from the mental model theory of deduction. Findings of Experiments 2 and 3 showed that some fallacies are consistently endorsed and others consistently resisted when people are asked to judge whether conclusions that are only possible follow necessarily. This finding was accounted for by the computational implementation of the model theory: Fallacies are made when the first mental model of the premises considered supports the conclusion presented.
Believability and syllogistic reasoning
Cognition, 1989
This paper is about syllogistic reasoning, i.e., reasoning from such pairs of premises as, All the chefs are musicians; some of the musicians are painters. We present a computer model that implements the latest account of syllogisms, which is based on the theory of mental models. We also report four experiments that were designed to test this account. Experiments 1 and 2 examined the strategies revealed by the participants' use of paper and pencil as aids to reasoning. Experiment 3 used a new technique to externalize thinking. The participants had to refute, if possible, putative conclusions by constructing external models that were examples of the premises but counterexamples of the conclusions. Experiment 4 used the same techniques to examine the participants' strategies as they drew their own conclusions from syllogistic premises. The results of the experiments showed that individuals not trained in logic can construct counterexamples, that they use similar operations to those implemented in the computer model, but that they rely on a much greater variety of interpretations of premises and of search strategies than the computer model does. We re-evaluates current theories of syllogistic reasoning in the light of these results.