How (far) can rationality be naturalized? (26 pages)

how (far) can rationality be naturalized • abstract

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Synthese (2012) 187:243–268
DOI 10.1007/s11229-011-0030-6

How (far) can rationality be naturalized?

Gerd Gigerenzer

· Thomas Sturm

Received: 30 September 2011 / Accepted: 30 September 2011 / Published online: 1 November 2011
© Springer Science+Business Media B.V. 2011


The paper shows why and how an empirical study of fast-and-frugal heu-

ristics can provide norms of good reasoning, and thus how (and how far) rationality
can be naturalized. We explain the heuristics that humans often rely on in solving
problems, for example, choosing investment strategies or apartments, placing bets in
sports, or making library searches. We then show that heuristics can lead to judgments
that are as accurate as or even more accurate than strategies that use more information
and computation, including optimization methods. A standard way to defend the use
of heuristics is by reference to accuracy-effort trade-offs. We take a different route,
emphasizing ecological rationality (the relationship between cognitive heuristics and
environment), and argue that in uncertain environments, more information and compu-
tation are not always better (the “less-can-be-more” doctrine). The resulting naturalism
about rationality is thus normative because it not only describes what heuristics people
use, but also in which specific environments one should rely on a heuristic in order
to make better inferences. While we desist from claiming that the scope of ecological
rationality is unlimited, we think it is of wide practical use.



· Judgment and decision-making · Heuristics · Uncertainty

It is often doubted that rationality can be naturalized. Is it not preposterous to derive
norms of reasoning from descriptive statements of empirical science? How is it pos-
sible to explain norms scientifically? And is reason not in part the source of a pri-
ori, strictly universal knowledge claims? The first of these three skeptical questions

G. Gigerenzer (



Max Planck Institute for Human Development, Berlin, Germany

T. Sturm
Department of Philosophy, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain


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