Mos Geometricus and the Common Law Mind: Interrogating Contract Theory
| DOI | http://doi.org/10.1111/1468-2230.12388 |
| Date | 01 January 2019 |
| Author | Shivprasad Swaminathan |
| Published date | 01 January 2019 |
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Mos Geometricus and the Common Law Mind:
Interrogating Contract Theory
Shivprasad Swaminathan∗
Euclidian theories have it that there exist one or a small number of apex principles from
which the entire fasciculus of rules of contract law can be logically deduced. Two arguments
are marshalled against the Euclidian project. First, that it has been unsuccessfully attempted
before – in the form of the nineteenth century contract law treatise which emulated the civil
lawyer’s rationalistic model, mos geometricus – cautioning us against setting much store by its
present reincarnation. Second, that the common law’s methodology makes it resistant to this
form of theorising. Euclidian theory presupposes a picture of rules on which: a) cases involve
an application of logically prior rules; b) rules are reliably identifiable by different actors in the
legal system; and c) rules normatively range over an indefinite spectrum of future cases. It will
be argued that the common law defies this picture of rules thus rendering Euclidian theory
analytically impossible.
THE EUCLIDIAN PARADIGM AND LEGAL THEORY: A FIRST LOOK
Theorising about contract law has progressed geometrically in the common
law world since the 1980s in both possible senses of ‘geometric progression’.1
For one, there is the sheer proliferation of such accounts – enough to prompt
the Clarendon Law Series to bring out a mappa mundi on ‘contract theory’,
thereby recognising its autonomy as a ‘major field’ of legal thought.2For
another, the theories are typically modelled along Euclidian lines. Euclidian
geometry begins with a small number of axioms and deduces a whole body of
rules as following logically from that starting point. Similarly, these theories of
contract are arranged as if there is one or a small number of overarching apex
principles from which the entire body of rules of contract law might follow
in a deductive framework.3These apex principles might be consequentialist or
∗Associate Professor, O. P. Jindal Global University, Delhi (NCR) India. Versions of this paper were
presented at the Stanford-Pennsylvania International Junior Faculty Forum at Stanford University;
‘Moral Limits of Markets’ at University of Amsterdam;and ‘LegArg’ at European Law Faculty, Ljubl-
jana. I am grateful to Stewart Macaulay, Shyam Balganesh, and Aditi Bagchi who were discussants at
Stanford and Amsterdam; and to Lawrence Freidman,Jianlin Chen, Scott Stephenson, Helen Ir ving,
Martijn Hesselink, Ivan Padjen, Marko Novakand Br uce Anderson, along with others who partici-
pated in the discussions on these occasions. I also wish to thank Rogelio Perez-Pedromo, Reinhard
Zimmermann, Yugank Goyal, Martin Mork, Mohsin Raza Khan, Matthew John, Prashant Iyengar,
Chiara Picciau and Sabine Tsuruda; and the anonymous referees for their valuable suggestions.
1 The inflection point, it would appear, was the publication in 1981 of C. Fried, Contract as Promise
(Cambridge, MA: Harvard University Press, 1981).
2 S. Smith, Contract Theory (Oxford: OUP, 2004). The Clarendon Law Series seeks to provide
‘overviews of major fields of law and legal thought’.
3 M.A. Eisenberg, ‘The Theor y of Contracts’ in P.Benson (ed), The Theor y of ContractLaw: New
Essays (Cambridge: CUP, 2001) 206. Eisenberg calls them ‘metric’ theories.
C2019 The Author. The Modern Law Review C2019 The Modern Law Review Limited. (2019) 82(1) MLR 46–70
Published by JohnWiley & Sons Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK and 101 Station Landing, Medford, MA 02155, USA
Shivprasad Swaminathan
deontological.4The justification of the apex principles is transmitted down to
every putative contract law case. This model of theorising is also fast becoming
the industry-standard in other areas of private law in the common law world.5
Assessing the congruity of this form of theor ising with the common law mind,
this paper will marshal two arguments against it. First, that traditionally the
common law has consciously eschewed this form of theorising, except for a
brief spell in the nineteenth century,6but that project eventually came a crop-
per – a smidgen of genealogical detail that should caution us against setting
much store by its present reincarnation. Secondly, that there are elements in
the common law’s methodology that necessarily make it resistant to this form
of theorising, which, incidentally, could also illuminate the abortive nineteenth
century project. Therefore, the project of arranging the common law of con-
tract along the lines of a Euclidian system, it will be argued, is bound to end
up being the legal theorist’s china egg: however much they may brood on it,
nothing will come out of it.
Euclid is not meant merely as metaphor for this model of theorising. The
rationalist arrangement of the law these contract theories undertake continues
a long tradition of theorising – at home in the civil law tradition – which at its
inception was deliberately and self-consciously modelled along Euclidian lines.
It was Ren´
e Descartes who wrote the Euclidian paradigm into the charter of the
Enlightenment when he held that no human knowledge could claim the exalted
status of ‘science’ – he had the Aristotelian ideal of science in mind – unless
its laws could be arranged in a deductive system along Euclidian lines.7This
Cartesian assumption greatly influenced the shape that philosophical and legal
theorising took in Europe. In philosophy, the Cartesian assumption gave birth
to ‘rationalism’, whose leading lights were Blaise Pascal, Benedict Spinoza and
Gottfried Leibniz, Jean Domat and Christian Wolff.8Rationalist philosophers
took themselves to be elucidating a science of morals in which they emulated
the geometer’s method.9
The idea of mos geometricus in law was cut from the same Cartesian fabric.
Since law, like philosophy, was a science, it was to be understood ‘on the model
of classical geometry’.10 Just as in any other science, therefore, one could deduce
‘more geometrico’ all the rules of a legal system from ‘axiomatic principles’.11
4 P.A. Alces, ATheoryofContractLaw(New York, NY: OUP, 2011) 1-3. Varieties of contract
theory are discussed in the third section of the paper.
5 B. Bix, ‘The Promise and Problems of Universal, General Theories of Contract Law’ (2017) 30
Ratio Juris 391.
6 B. Bix, Contract Law: Rules, Theory, and Context (Cambridge: CUP, 2012) 147-148.
7 A. Wedberg, A History of Philosophy: Vol 2 (Oxford: Clarendon Press, 1982) 7, 32.
8ibid, 38.
9 Even down to our times, the geometric method prevails among philosophers in the rationalist
tradition. John Rawls, for instance, argues that we should strive for a ‘moral geometry’. See J.
Rawls, A Theory of Justice (Cambridge, MA: Harvard University Press, 1971) 121.
10 M. Hoeflich, ‘Law & Geometry: Legal Science from Leibniz to Langdell’ (1986) 30 American
Journal of Legal History 95, 100. This view goes back to Leibniz.
11 R.C. van Caenegem, A Historical Introduction to Private Law (Cambridge: CUP, 1992) 118.
‘Mos Geometricus’ (nominative) or ‘more geometrico’ (ablative) is Latin for manner or method of
geometry. In the literature, the two phrases are used interchangeably to describe the Cartesian
method which emulated that of the geometer, namely, that of logical deduction from axioms.
C2019 The Author. The Modern Law Review C2019 The Modern Law Review Limited.
(2019) 82(1) MLR 46–70 47
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