, Volume 167, Issue 2, pp 317–325 | Cite as

Logical fallacies as informational shortcuts

  • Luciano FloridiEmail author


The paper argues that the two best known formal logical fallacies, namely denying the antecedent (DA) and affirming the consequent (AC) are not just basic and simple errors, which prove human irrationality, but rather informational shortcuts, which may provide a quick and dirty way of extracting useful information from the environment. DA and AC are shown to be degraded versions of Bayes’ theorem, once this is stripped of some of its probabilities. The less the probabilities count, the closer these fallacies become to a reasoning that is not only informationally useful but also logically valid.


Affirming the consequent Bayes’ theorem Denying the antecedent Formal fallacies Rationality 


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  1. Aristotle, (1938). De Sophisticis Elenchis. On sophistical refutations (trans: Forster, E. S.). On with the Cosmos/by Furley, D. J. Cambridge, MA: Harvard University Press.Google Scholar
  2. Chater N., Oaksford M. (2008) The probabilistic mind: Prospects for Bayesian cognitive science. Oxford University Press, OxfordGoogle Scholar
  3. Floridi L. (2008) Understanding epistemic relevance. Erkenntnis 69(1): 69–92CrossRefGoogle Scholar
  4. Griggs R.A., Cox J.R. (1982) The elusive thematic-materials effect in Wason’s selection task. British Journal of Psychology 73: 407–420Google Scholar
  5. Hahn U., Oaksford M. (2006) A Bayesian approach to informal argument fallacies. Synthese, 152(2): 207–236CrossRefGoogle Scholar
  6. Hamblin C.L. (1970) Fallacies. Methuen, LondonGoogle Scholar
  7. Hansen, H.V., Pinto, R.C. (eds) (1995) Fallacies: Classical and contemporary readings. University Park, PA, Pennsylvania State University PressGoogle Scholar
  8. Josephson J.R. (2000) Smart inductive generalizations are abductions. In: Flach P.A., Kakas A.C. (eds) Abduction and induction: Essays on their relation and integration. Kluwer, Dordrecht, BostonGoogle Scholar
  9. Marcus S.L., Rips L.J. (1979) Conditional reasoning. Journal of Verbal Learning and Verbal Behavior 18: 199–224CrossRefGoogle Scholar
  10. Stein E. (1996) Without good reason: The rationality debate in philosophy and cognitive science. Clarendon Press, OxfordGoogle Scholar
  11. Verschueren N., Schroyens W., Schaeken W., d’Ydewalle G. (2001) Why do participants draw non-valid inferences in conditional reasoning? Current Psychology Letters: Behaviour, Brain, & Cognition 6:57–70Google Scholar
  12. Wason P.C. (1966) Reasoning. In: Foss B.M. (eds) New horizons in psychology. Penguin, Harmondsworth, pp 135–151Google Scholar
  13. Woods J., Walton D.N. (1982) Argument : The logic of the fallacies. McGraw-Hill Ryerson, TorontoGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.Research Chair in Philosophy of Information and GPI, School of HumanitiesUniversity of HertfordshireHatfieldUK
  2. 2.St Cross College and IEGUniversity of OxfordOxfordUK

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