ECONOMY

arry r. weingast & donald a. wittman 7
The second type of institutional analysis utilizes the above methodology to make
comparative statements about different institutions. For example, pivotal politics
models show the differences in behavior between a unicameral majoritarian system,
a bicameral system where each chamber uses majority rule, and a bicameral system
in which one chamber employs a filibuster rule allowing a minority of legislators to
prevent the passage of legislation. The first institution always results in the median
legislature’s ideal policy. The second institution creates a gridlock range of possible
policy choices—the set of points between the ideal policies of the median in each
chamber. Any status quo policy in this set is an equilibrium in that there does not
exist a majority in each chamber that can overturn it. The third institution extends
the set of status quo points that cannot be overturned even further: the possibility
of a filibuster means that only policies commanding 60 per cent in one chamber and
a majority in the other can overturn a policy, so more status quo policies are stable.
For a further discussion of these issues see Krehbiel (this volume) and Cutrone and
McCarty (this volume).
Third, a much smaller set of papers studies the structure of the legislature itself and
treats its institutions as endogenous. 5 Four different approaches have been used to
explain legislative structure: (1) legislator preferences, (2) committees as commitment
devices, (3) parties as transactions cost reducers, and (4) committees as information
providers. 6 We will now discuss each in turn.
1.1 Legislator Preferences
The simplest of the approaches bases legislative choice on legislator preferences
and relies on the “majoritarian postulate,” which holds that legislative policy and
procedural choices are made by majorities (Krehbiel 1991). In the context of
one-dimensional models of policy choice, the preference-based approach has the
following implications (Krehbiel 1993). First, policy choice corresponds to that of
the median legislator. Second, suppose that legislators join one of two parties, and,
further, that those to the right of the median largely join one party while those to the
left of the median largely join the other party.
Suppose that the status quo is to the right of the median and the proposed
legislation seeks to move policy left toward the median voter’s ideal. The “cutting
line” divides the set of voters into those favoring the status quo and those favoring
the proposal. In this context, the cutting line is that policy halfway between the
status quo and the proposed alternative (assuming that legislator utility functions
are symmetric). Since the status quo is to the right of the median, so too will be the
cutting line. The proposal makes every legislator to the right of the cutting line worse
off, so they vote against the policy; while every legislator to the left of the cutting line
is better off under the proposal and will vote for it.
⁵ Weingast 2002 surveysthismodeofanalysisindifferent contexts. Shepsle (this volume) provides a
variantonthesethemes.
⁶ Laver (this volume) covers some of these issues; see also the summary in Shepsle and Weingast 1995.