Law and the Evolutionary Turn: The Relevance of Evolutionary Psychology for Legal Positivism

• Published date: 01 September 2014
• Author: Arthur Dyevre
• DOI: http://doi.org/10.1111/raju.12049
• Date: 01 September 2014

Law and the Evolutionary Turn:

The Relevance of Evolutionary

Psychology for Legal Positivism

ARTHUR DYEVRE

Abstract. In the present essay, I consider the relevance of evolutionary psychology

(EP) for legal positivism, addressing the two main traditions in the legal positivist

family: (1) the tradition I identify with the works of Hart and Kelsen and

characterize as “normativist,” as it tries to describe law as a purely or, at least, as

an essentially normative phenomenon, while remaining true to the ideal of scien-

tific objectivity and value-neutrality; (2) the tradition I broadly refer to as “legal

realism,” which equates law with adjudication and “legal science” with the task of

explaining judicial behaviour.

1. Introduction

After the “critical legal studies” and the “law and economics” movement, “law and

evolutionary biology” seems well on its way to becoming a leading force in

American law schools, and the wave could well spill over to European law faculties

(Elliott 1996; Jones 1996, 2000, 2004, 2005; Jones and Goldsmith 2005; Zywicki 1999;

Załuski 2009). That evolutionary theory will eventually revolutionize legal thinking

may not be as obvious as the most enthusiastic advocates of the new creed would

have us believe. Still, the movement has already spawned a rapidly expanding

literature, which suggests that lawyers and legal scholars may have something

useful to learn from Darwin and his twenty-first century disciples. A brief review

of recent journal articles and monographs reveals that insofar as scholars regard

evolutionary biology as a source of potential insights for the law, it is primarily as

a source of insights for law-making or for the normative discipline of legal

philosophy. The relevance of evolutionary thinking for law is in answering ques-

tions such as “How can evolutionary biology help us design better, more efficient

legal rules?” (Jones 2000) or “What values and political philosophy can the law

effectively realize given what evolution says about human nature?”1(Załuski 2009,

1An illustration is given by Zaluski (2009, 79), who argues that the view of human nature

emerging from evolutionary theory should determine to a certain degree our choice of

political philosophy.

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79). As these questions suggest, the approach implicit in the work of those who

purport to explore the interconnections between law and evolutionary theory is

essentially normative. Evolutionary biology is relevant to law because lawyers seek

to make the law more efficient and effective. Whether and to what extent evolu-

tionary insights could also inform positivist theories of law and positivist

approaches to the study of legal systems, on the other hand, is a question that has

not attracted much attention.2On this score, law differs from economics and other

social sciences, where the findings and methods of post-Darwinian evolutionary

theory have been mainly deployed not as tools to improve policy-making but

rather as a basis to revisit the theoretical foundations of disciplines conceived in

primarily positive terms.3

In the present essay I consider the relevance of evolutionary psychology (EP) for

positivist theories of law. Although I focus on EP because it has made the boldest

claim to re-examine the behavioural assumptions that provide the mainstay of the

modern social sciences, much of what I say is relevant for the broader debate on

the application of evolutionary approaches—of which EP is only one among several

competing research paradigms—to law and legal thinking. In my analysis I address

the two main traditions in the legal positivist family4: (1) the tradition I identify

with the works of H.L.A. Hart and Hans Kelsen and call the “normativist”

tradition, as it tries to describe law as a purely or, at least, as an essentially

normative phenomenon while remaining true to the ideal of scientific objectivity

and value-neutrality; (2) the tradition I broadly refer to as “legal realism,” which

equates law with adjudication and “legal science” with the task of explaining

judicial behaviour. On the assumption that the claims of EP are correct, I try to

2Załuski (2009, 132) touches on the issue when he notes that “legal positivism [. . .] does

not postulate an interdisciplinary approach to law”. In any case, he sees his own work

as articulating a new theoretical current alongside legal positivism, Kelsen’s pure theory of

law, natural law, legal hermeneutics, legal realism, law and economics and the Critical

Legal Studies movement rather than as a source of insights for these various strands in

legal philosophy (ibid., 132–7).

3In economics see, e.g., Pelikan (2011) and Hodgson (2002, 2004). See also the argument of

prominent evolutionary psychologists in Cosmides and Tooby (1994) and Tooby and

Cosmides (2007). For a spirited defense of the view that sociologists should pay heed to the

findings of evolutionary theory too, see Freese et al. (2003) and Lopreato and Crippen (2001).

For a similar argument in political science, see Hibbing and Smith (2007) and Somit and

Peterson (2003).

4I realise that counting legal realism as a member of the legal positivist family may seem odd.

The term “legal positivism” is itself ambiguous. Many still equate it with formalistic doctrines

according to which statutes are always clear and constitute the only valid source of law. For

this reason, legal realism, with its emphasis on judicial law-making and judicial discretion, is

sometimes viewed as a reaction against legal positivism. However, this view does not apply

for the kind of positivism advocated by Hart and Kelsen, who cannot be suspected of

embracing any form of statutory formalism. As shown by Leiter (2001), the theoretical

position articulated by Hart (1961) is not inconsistent with the research programme of

American legal realists. On the contrary, the realist project seems to presuppose a theory of

law along the lines of Hart’s. More to the point, though, what justifies my lumping together

Hart and Kelsen with legal realists (at least American ones) is that all these approaches

fundamentally treat law as a social fact, although they differ in the research question they

emphasize. I am not alone in characterizing legal realism as a branch of legal positivism; see,

e.g., Grzegorczyk et al. 1992.

Law and the Evolutionary Turn 365

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