Do supermajority rules really deter extremism? the role of electoral competition 1
| Author | Daiki Kishishita,Atsushi Yamagishi |
| Published date | 01 January 2022 |
| DOI | 10.1177/09516298211061161 |
| Date | 01 January 2022 |
| Subject Matter | Articles |
Do supermajority rules really
deter extremism? the role of
electoral competition
1
Daiki Kishishita
Department of Business Economics, School of Management, Tokyo
University of Science. E-mail: daiki.kishishita@gmail.com
Atsushi Yamagishi
Department of Economics, Princeton University.
Abstract
This study investigates how supermajority rules in a legislature affect electoral competition.
We construct an extensive-form game wherein parties choose policy platforms in an election.
Post election, the policy is determined based on a legislative voting rule. At symmetric equilibrium,
supermajority rules induce divergence of policy platforms if and only if the parties are sufficiently
attached to their preferred platform. Thus, supermajority rules may not always lead to moderate
policies once electoral competition is considered.
Keywords
Divergence, Probabilistic voting, Supermajority, Legislative bargaining
1. Introduction
Extreme policies undermine the responsiveness of democracy and benefit only a small
group of people at the cost of citizens’welfare. Supermajoritarianism in the legislature
is a potent method of preventing extremism because it ensures that even the majority
party cannot pass a bill without the minority party’s approval as long as the former’s
seats do not exceed a supermajority threshold. Consequently, the majority party compro-
mises with the minority party, mitigating extremism. Such ideas are shared widely. For
Corresponding author:
E-mail: ayamagishi@princeton.edu
Article
Journal of Theoretical Politics
2022, Vol. 34(1) 127–144
© The Author(s) 2021
Article reuse guidelines:
sagepub.com/journals-permissions
DOI: 10.1177/09516298211061161
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example. Ackerman (2000 ) recommends a sup ermajority req uirement by the U. S.
Senate to confirm nominations to the Supreme Court so that the appointed members
become moderate. Knight (2000) investigates supermajority requirements for tax
increases in the U.S. local states and finds that they significantly reduce tax rates. An
implicit or explicit supermajority rule often exists that enables the minority party to
affect policymaking.
2
The central objective of this study is to uncover an overlooked aspect of supermajor-
itarianism that might lead to extreme policies. Particularly, we focus on the effect of
supermajority rules on electoral competition. As the celebrated median voter theorem
(Downs, 1957) suggests, electoral competition works as an instrument to deter extrem-
ism. The theorem predicts the convergence of policy platforms when two office-seeking
parties simultaneously commit to policy platforms in a unidimensional policy space. This
implies that electoral competition deters extremism when parties can commit to policies,
that is, it is an instrument to prevent extremism.
We show that supermajoritarianism may dampen the power of electoral competition,
which is another important instrument to prevent extremism, and induce divergence of
policy platforms. Currently, there is a lingering controversy about whether the superma-
jority requirement should be weakened.
3
This study contributes to this debate by showing
that supermajoritarianism unintentionally mitigates electoral competition and exacerbates
policy divergence.
For this purpose, we construct a model with two policy-motivated parties in a
single-dimensional policy space. In addition to the incentive of the final policy
output being proximate to their ideal policies, parties receive the psychological cost
of promising platforms diverging from their ideal policies, irrespective of the final
policy output. Considering these incentives, the parties determine their policy plat-
forms.
4
The electoral rule entails a single-member constituency system. There are a
finite number of homogeneous constituencies, and one legislator is elected from one
constituency. Given the electoral platforms, the number of seats per party is deter-
mined during the election stage. Subsequently, the policy output is determined in
the legislature based on a specific voting rule. The majority party proposes a bill,
and the minority party decides whether it wants to oppose the bill or not. When the
former’s seats are less than the supermajority requirement, the latter’s approval is
necessary to pass a bill.
For the election, we adopt a probabilistic voting model. In each constituency,
parties face aggregate uncertainty about voters’preferences and must decide their
platforms before this uncertainty is resolved. This is a common shock across voters
within a district, but an idiosyncratic shock across districts. Since the number of dis-
tricts is finite, idiosyncratic shocks to voters’preferences are not completely offset.
Thus, parties face uncertainty about electoral outcomes when choosing their policy
platforms. This uncertainty is one of the sources of policy divergence when parties
are policy-motivated (e.g., Wittman, 1983; Calvert, 1985; Roemer, 1994). This
implies that parties’policy platforms do not fully converge on the representative
voters’ideal policy.
We analyze the effect of legislative voting rules on policy platforms in elections. Our
key finding is that the divergence of policy platforms generated by aggregate uncertainty
128 Journal of Theoretical Politics 34(1)
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