ECONOMY

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Outcome
I II III IV
m r 2r−m
m
No policy change
Gridlock Interval
r 2r − m Status quo, q
Fig. 12.3 Equilibrium in the procedural cartel theory
Consider analytics first. The core model in Cox and McCubbins’s (2005) Setting the
Agenda is clearly recognizable as the gatekeeping model of Denzau and Mackay (1983).
Much as the pivotal politics theory is reducible to four players and four stages, the
Denzau–Mackay/Cox–McCubbins theory is reducible to two players and two stages.
In stage one, an agenda-setter denoted by r —e.g. the Republicans’ median voter—
has “unconditional agenda power,” by which the authors mean the ability to block
any and all attempts to change the exogenous status quo. In stage two, if and only if
a stage-one bill is proposed, the full legislature selects the median voter’s ideal point
under an open rule. The gatekeeping assumption has an immediate implication: a
necessary condition for policy change is that a majority of the majority party prefers
the legislature’s median voter’s ideal point to the status quo. Conversely, gridlock
prevails whenever this condition is not met.
Figure 12.3 illustrates the equilibrium of the gatekeeping model in parallel fashion
with the pivotal politics diagram in Figure 12.2. Clearly, the majority party median, r ,
resembles the pivotal voters f and v in pivotal politics theory. His consent, like that of
the veto or filibuster pivot, is a necessary and sufficient condition for policy change.
Although the party cartel theory satisfies the generic features of pivot theories,
several distinctions between it and the earlier pivotal politics model are subjects of
ongoing debate in the field.
First, the procedural pivot (i.e. majority party gatekeeper) in the cartel model is not
in general indifferent between the final policy (the legislative median) and the status
quo, as is often the case for pivots in the pivotal-politics model. This observation
follows from the fact that the majority party median r is not a constraint against
which other players optimize but rather plays the role of dictatorial obstructionist
whenever the status quo lies within |r − m| units of his ideal point, r .
Second, like the pivotal politics theory, the procedural cartel theory also provides
an account for gridlock. However, within the cartel theory’s relatively large
range of status quo points that cannot be changed in equilibrium—namely, those in
(m, 2r − m)—half of these policies (r, 2r − m) are not Pareto optimal with respect to