Behavioral and Brain Sciences

Table of Contents - October 2011 - Volume 34, Issue 05  

Open Peer Commentary

The “is-ought fallacy” fallacy

Mike Oaksforda1 and Nick Chatera2

a1 Department of Psychological Sciences, Birkbeck College, University of London, London, WC1E 7HX, United Kingdom. mike.oaksford@bbk.ac.uk http://www.bbk.ac.uk/psyc/staff/academic/moaksford

a2 Behavioural Sciences Group, Warwick Business School, University of Warwick, Coventry CV4 7AL, United Kingdom. nick.chater@wbs.ac.uk http://www.wbs.ac.uk/faculty/members/Nick/Chater-

Abstract

Mere facts about how the world is cannot determine how we ought to think or behave. Elqayam & Evans (E&E) argue that this “is-ought fallacy” undercuts the use of rational analysis in explaining how people reason, by ourselves and with others. But this presumed application of the “is-ought” fallacy is itself fallacious. Rational analysis seeks to explain how people do reason, for example in laboratory experiments, not how they ought to reason. Thus, no ought is derived from an is; and rational analysis is unchallenged by E&E's arguments.

(Online publication October 14 2011)

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