EXPRESS: The Bright Homunculus in our Head: Individual Differences in Intuitive Sensitivity to Logical Validity

Classic dual process theories of human reasoning attribute explicit reasoning to effortful, deliberative thinking. According to these models, intuitive processes lack any access to the formal rules of logic and probability and hence rely exclusively on superficial problem features to determine a response. However, in recent years, researchers have demonstrated that reasoners are able to solve simple logical or probabilistic problems relatively automatically, a capability which has been called ‘logical intuition’. In four experiments, we instructed participants to judge the validity (Experiments 1 and 4), likeability (Experiments 1, 2, and 3) and physical brightness (Experiments 2, 3, and 4) of the conclusion to several reasoning problems. Brightness judgments were made by evaluating the font shade brightness of the argument’s conclusion. Participants were also asked to complete a range of individual differences measures, drawing on cognitive ability and cognitive style, in order to evaluate the extent to which ‘logical intuitions’ were linked to measures of deliberative reasoning. The results showed that participants judged the conclusion of logically valid statements to be more valid, more likable and more physically bright. Participants with higher cognitive ability and unlimited processing time showed greater effects of logical validity in their liking judgments (varied across experiments). However, these effects were absent in the brightness tasks, suggesting that logic effects observed under instructions to judge conclusion brightness are a purer measure of ‘logical intuition’. We discuss the implications of our findings for recent dual process theories of human reasoning.

Logical Intuition Is Not Really About Logic

Recent research suggest that reasoners are able to draw simple logical or probabilistic inferences relatively intuitively and automatically, a capacity which has been termed “logical intuition” (see, for example, De Neys & Pennycook, 2019). A key finding in support of this interpretation is that conclusion validity consistently interferes with judgments of conclusion believability, suggesting that information about logical validity is available quickly enough to interfere with belief judgments. In this paper we examined whether logical intuitions arise because reasoners are sensitive to the logical features of problem or another structural feature that just happens to aligns with logical validity. In three experiments (N = 113, 137, and 122), we presented participants with logical (determinate) and pseudo-logical (indeterminate) arguments and asked them to judge the validity or believability of the conclusion. Logical arguments had determinately valid or invalid conclusions, whereas pseudo-logical arguments were all logically indeterminate, but some were pseudo-valid (possible ‘strong’ arguments) and others pseudo-invalid (possible ‘weak’ arguments). Experiments 1 and 2 used simple Modus Ponens and Affirming the Consequent structures; Experiment 3 used more complex Denying the Antecedent and Modus Tollens structures. In all three experiments, we found that pseudo-validity interfered with belief judgments to the same extent as real validity. Altogether, these findings suggest that whilst people are able to draw inferences intuitively, and these inferences impact on belief judgments, they are not ‘logical intuitions.’ Rather, the intuitive inferences are driven by the processing of more superficial structural features that happen to align with logical validity.

Revisiting the Boy-and-Girl Fallacy at Nicomachean Ethics I 2

This paper proposes a new reading of Nicomachean Ethics I 2 1094a18-22 with a view to solving the problem that the argument this passage contains would be invalid because it apparently commits a quantifier shift to reach its conclusion. On the reading advocated in this paper, no fallacy is committed, and the argument is sound provided one reads the conclusion at 1094a21-22 in the way the manuscript Marcianus 213 invites us to do. Grammatical considerations are produced to shore up the logical validity of the argument.

Brain electrical traits of logical validity

Neuroscience has studied deductive reasoning over the last 20 years under the assumption that deductive inferences are not only de jure but also de facto distinct from other forms of inference. The objective of this research is to verify if logically valid deductions leave any cerebral electrical trait that is distinct from the trait left by non-valid deductions. 23 subjects with an average age of 20.35 years were registered with MEG and placed into a two conditions paradigm (100 trials for each condition) which each presented the exact same relational complexity (same variables and content) but had distinct logical complexity. Both conditions show the same electromagnetic components (P3, N4) in the early temporal window (250–525 ms) and P6 in the late temporal window (500–775 ms). The significant activity in both valid and invalid conditions is found in sensors from medial prefrontal regions, probably corresponding to the ACC or to the medial prefrontal cortex. The amplitude and intensity of valid deductions is significantly lower in both temporal windows (p = 0.0003). The reaction time was 54.37% slower in the valid condition. Validity leaves a minimal but measurable hypoactive electrical trait in brain processing. The minor electrical demand is attributable to the recursive and automatable character of valid deductions, suggesting a physical indicator of computational deductive properties. It is hypothesized that all valid deductions are recursive and hypoactive.

The Validity of the Internalized Argumentation Skills Test for Chemistry Students

This study aims to produce a package of questions measuring internalized argumentation skills (IAS) that meet the requirements of logical validity (content and construct) and empirical validity. The research follows Fenrich’s development model. The implementation of the test package to test the empirical validity involved 30 participants, students of the Chemistry Education Study Program. The research data were analyzed descriptively. The results of the research, a package of IAS measuring questions for chemistry students has been successfully developed. The IAS measuring test package consists of five questions with details of one easy level question, three medium level questions, and one difficult level question. The package of questions developed has met the requirements of logical validity (content and construct) and empirical validity.

The Epistemology of Logic

This chapter shows that unrestricted inferentialism/conventionalism leads to a naturalistically satisfying account of our a priori knowledge of logical validity. The chapter first lays the groundwork by discussing the general question of what conditions arguments need to meet in order to lead to knowledge of their conclusions. Following Boghossian, the chapter then argues that inferentialism/conventionalism is particularly well posed to allow rule-circular arguments to lead to a priori knowledge of the validity of our basic rules. Restricted inferentialists were often forced to complicate and sometimes abandon their accounts of logical knowledge in the face of bad company. By contrast, unrestricted inferentialism has no problem at all with bad company. All told, conventionalism gives a naturalistic account of our a priori knowledge of logic.

Light as a Metaphor for Truth

This chapter assesses Hans Blumenberg's essay, “Light as a Metaphor for Truth” (1957). With this essay, Blumenberg formulated the seed of the project for which he is, at least in Germany, best known: his “metaphorology.” While metaphorology initially seemed to be an extension of conceptual history — a research project aimed at investigating the semantic changes to central concepts of philosophy — it at the same time called into question the very centrality of concepts and terminologies as the only and authentic bearers of philosophical thought. Instead, it makes the case for studying the role pre- and nonconceptual speech plays in the language of philosophy. Where traditionally theories of truth would be interpreted in terms of their propositional content or logical validity, Blumenberg's article instead looks at the metaphors with which truth is described and which operate, as he puts it in the subtitle, “At the Preliminary Stage of Concept Formation.”