Structural Incentives for Political Party Polarization
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Date
2017
Authors
Smith, Connor
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Politics is often thought of as a pie cut in half and split between republicans and democrats. A
more accurate representation would be a pie cut into several uneven slices; most of the small pieces
would go to the democrats and the few large slices would go to republicans. The existing literature on
political parties indicates that parties are not mirror opposites of one another. Issue density is not uniform
among the parties. Since the New Deal, democrats have pushed extensive policy from Social Security to
new roads and dams. The trend to expand the scope of government policy continues today in the form of
universal healthcare, combating global warming, and gay rights. The tendency of democrats to expand
their policy agenda stems from the makeup of the party. Unlike republicans, the Democratic party is
composed of a coalition of interest groups. Republicans, in contrast, can be described as ideological and
have held consistent over time. Republicans are more easily thought of in terms of big ideological
principles that include low taxes, defense, and family values. Republicans, being more ideological, have a
few core tenants. Democrats, being a coalition of interest groups, have a wide and diverse set of principles
but less support behind each issue area.
Given two political parties, one with a smaller but deeper set of beliefs and a second with a wider
and shallower set of beliefs, the group with a smaller number of principles will find it relatively more
difficult to compromise. Since politicians are single-minded seekers of reelection, they try to capture a
comfortable number of votes to become reelected; however, if the party with the smaller number of
principles were to compromise on a single principle, they would risk losing a proportionally greater
number of voters. For instance, let us assume two political parties ‘R’ and ‘D’. R holds two principles ‘1’
and ‘2’, while D holds principles ‘3’, ‘4’, ‘5’, ‘6’, and ‘7’. If R compromises on principle 2 to gain access
to voters from principle area 3, they risk losing half of their voter base, assuming 1 and 2 contain equal
numbers of voters who care deeply about that principle. Whereas if D compromises on principle 3 to gain
access to voters from principle area 2 they risk only losing one-fifth of their voter base, assuming 3, 4, 5,
6, and 7 all contain equal numbers of voters who care deeply about that issue. Therefore, republicans are
disincentivized from compromising while democrats have an incentive to work with republicans.
Democrats compromise because they are likely to gain more votes from sacrificing small areas for a
bigger traditionally republican area.