Academic journal article Melbourne University Law Review

Collective Irrationality and the Doctrine of Precedent

Academic journal article Melbourne University Law Review

Collective Irrationality and the Doctrine of Precedent

Article excerpt

Appellate adjudication is committed to decision-making by groups and it is committed to decision-making by adherence to precedent. Those commitments are in tension. Group decision-making is inherently susceptible to collective irrationality in the form of internal inconsistency. This presents particular problems for achieving consistency through precedent-based decision-making. Exploring insights from the emerging interdisciplinary literature on judgment aggregation, we sketch a defence of how the common law has traditionally managed these thorny issues.


  I Introduction
 II Collective Irrationality
      A Meaning of 'Collective Irrationality'
      B Illustration of Collective Irrationality
      C Avoiding Collective Irrationality
      D A Dilemma
III Doctrine of Precedent
      A Ignoring Unnecessary Reasoning
      B Ignoring Dissenting Opinions
      C No Ratio Decidendi
 IV Conclusion

   [W]here the Court, although coming to a firm conclusion in its
   curial order, does so upon different grounds ... it imparts into
   the legal principles enunciated under a system of precedents, an
   uncertainty which is to be deplored. (1)

   Inconsistency is inevitable ... [D]emands for perfect consistency
   can not be fulfilled, and it is inappropriate to condemn the
   Court's performance as an institution simply by pointing out that
   it sometimes, even frequently, contradicts itself. (2)


Decision-making by groups, because it depends upon aggregating decisions by individuals, is inherently susceptible to internal inconsistency. Decision-making by adherence to precedent, because it strives to treat like cases alike, is inherently committed to achieving consistency over time. The common law system of decision-making utilises both groups (multi-member appellate courts) and adherence to precedent (stare decisis). The common law system of decision-making is therefore inherently susceptible to inconsistency within particular decisions, yet inherently committed to consistency between those decisions. How does the common law reconcile that susceptibility with that commitment?

The beginnings of an answer to the question can be found in the rational function performed by some of the formal rules of the doctrine of precedent. By exploring and applying the insights that are emerging from a growing interdisciplinary literature on judgment aggregation, we sketch a defence of the common law's traditional requirements that, when ascertaining of an appellate decision whether it has a ratio decidendi that binds subsequent courts and if so what that ratio decidendi is, one should ordinarily exclude from consideration reasoning that was unnecessary to the decision and dissenting opinions.

In a previous article, one of us examined the practice of group decision-making in appellate courts from the perspective offered by Condorcets jury theorem--the mathematical result that a group deciding by majority rule is, under certain reasonable conditions, more likely to arrive at a correct decision than any individual member of the group deciding alone. (3) That article considered the conditions under which the theorem holds, principally the decisional competence of the individual members of the group and the decisional independence of the individual members of the group, and identified some of the practical issues that confront multi-member appellate courts in that regard. The article did not set out to address in detail the complications presented by composite propositions or the related issue of the inherent susceptibility to internal inconsistency in group decision-making. Nor did it set out to consider the problems that can arise when groups seek to make multiple decisions systematically over time. Those matters are now taken up in this article.

In Part II, we identify the problem of collective irrationality: how, in group decision-making contexts, the need to aggregate individual decisions is attended by an inherent susceptibility to inconsistency. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed


An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.