The Reasoning Test Psychologists Still Can't Explain

Episode Summary

Executive Summary: The episode explains the Wasson Selection Task, a classic reasoning puzzle most people fail, and argues that the difficulty reveals a deeper truth: humans are not naturally built for abstract falsification, but for social reasoning, norm enforcement, and communication. Through logic, science, and examples like bar-age rules, confirmation bias, and moral taboos, the hosts suggest we reason more to justify conclusions than to discover them.

Main Topics: The Wasson Selection Task (Priority: 5/5): A four-card logic puzzle from 1966 used to study human reasoning. The hosts walk through the original A/G/7/8 version and explain that the correct cards are A and 8 because they test the rule and its possible violation. Abstract vs. social framing (Priority: 5/5): The same logical structure becomes far easier when framed socially (e.g., underage drinking in a bar). This contrast is used to show that people reason more effectively about obligations and norms than abstract symbols. Logic, modus ponens, and modus tollens (Priority: 4/5): The episode explains conditional reasoning using antecedent/consequent language and shows why A and 8 correspond to searching for counterexamples, not just confirming the rule. Confirmation bias and counterexample neglect (Priority: 5/5): The discussion broadens from puzzles to science, arguing that people naturally seek confirming evidence and struggle to hunt for disconfirming cases, even when falsification is the most informative strategy. Evolutionary/social theories of reasoning (Priority: 5/5): Cosmides and Tooby’s view is presented: reasoning evolved mainly for social cooperation, communication, and detecting rule violations, not for abstract truth-finding. Phatic communion and everyday social language (Priority: 3/5): The hosts use greetings and formulaic exchanges ('you too,' 'you all right?') to show how humans prioritize social signaling over literal content in everyday communication. Moral reasoning and taboos (Priority: 4/5): Jonathan Haidt’s 'harmless taboo violations' are introduced to illustrate that moral judgments often appear before reasons; we then rationalize them afterward.

Key Arguments: The Wasson Selection Task is difficult because humans are poor at spontaneously searching for counterexamples in abstract settings. The exact same logical structure is much easier when embedded in a socially meaningful norm like age-restricted drinking. The correct strategy is to test the antecedent case (A/beer drinker) and the possible violation case (8/underage person), not merely confirm the rule. Science itself depends on falsification, yet everyday human cognition is biased toward confirmation rather than refutation. Reasoning likely evolved for social coordination and justification, so we often generate reasons after intuitively reaching a conclusion. People resist counterexamples by reinterpreting or dismissing them, as shown by the platypus anecdote and moral taboo examples. Public communication fails when it assumes the problem is merely a deficit of information; worldview, identity, and emotion shape acceptance of evidence.

Data Points: Original Wasson Selection Task success rate: 10% - Wasson’s 1966 original report of the A/G/7/8 puzzle Replicated success rate across studies: ~4% - The hosts cite later replications of the original abstract version Typical response pattern: 46% choose A and 7; 33% choose A only; 7% choose A, 7, and 8; 4% choose A and 8 - Distribution of answers in the original selection task Age-rule analogy: 12 and 35; soda and beer - A social version of the task used to show the logic becomes intuitive Logic terminology: Antecedent = P; consequent = Q - Explaining conditional reasoning and the structure of the puzzle Hidden genome claim: Genes are only 2% of DNA - Sponsor segment about cancer research and the 'dark genome'

Pivotal Quotes: "The test is called the Wasson Selection Task, and it was developed in 1966 by Peter Cathcart Wasson." — Michael Stevens: Introduction to the central reasoning puzzle "We use conclusions to come to reasons." — Hannah Fry: Discussion of Mercier and Sperber’s social theory of reasoning "You cannot argue or maths your way into changing people's minds or persuading them." — Hannah Fry: Debate about science communication and the deficit model

Implications: Listeners are encouraged to see reasoning as socially evolved and often confirmation-biased, which matters for science communication, politics, moral debate, and education. Better persuasion may require social trust and shared norms, not just more facts.