POLSCI 318 Lecture Notes - Lecture 15: Median Voter Theorem, Supermajority, Ideal Point
4 May 2018
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Congress and President
10.26.16 Lecture Notes – Pivotal Politics
x Pivotal politics theory only takes the formal presidential veto seriously
x Unidimensional policy space assumption (judged on Euclidean distance) is questionable
o Can conceive of two-dimensional space
x Policy itself does not have more than one component according to pivotal politics theory
x Chapter 1: tells us what he sets out to do and what he is responding to
o Create a theory of lawmaking that takes seriously the president in the policy-making process
o Looking to identify who is pivotal amongst the members of House and Congress
o Whose preference is pivotal to the lawmaking process?
▪ The median legislator
▪ A veto point
▪ A filibuster point
o Gridlock – a majority of legislators prefer a policy, yet they cannot make the policy enacted
▪ Not necessarily partisan – gridlock can occur even during unified government
▪ Gridlock is very common but not constant
o Wants to create a theory for why gridlock behaves in that pattern
o Winning coalitions in America tend to be super-majoritarian
▪ Theory has to account for the size of these majorities
Response to theories (COMPARE EMPIRICAL REALITIES IN THE MOST RECENT CONGRESS TO WHAT WILL BE
PREDICTED BY THESE THEORIES)
x Responsible party government thesis – if there is unified government, they can enact their party
platform completely unadulterated by the minority view
o Under this view, gridlock will be rare, especially under conditions of unified government
x Conditional party government – developed by Aldrich and Rodhe – interparty differences and
intraparty homogenous
o Majority party will have the power to pass policies that are noncentrist and skewed towards
their preferences
o Does not account for the empirical pattern for the size of the coalitions and patterns of gridlock
x Divided and unified government matters
o Conditions of divided and unified government account for gridlock
o David Mayhew found that Congress is just as productive during unified and divided
governments
x Median voter theorem posits that if you have an odd number of members of a majoritarian voting
body and have them ordered in an issue-space and they have single-peaked preferences, then the
eventual outcome will always be the preferences of the median voter
o Policies that are passed will be those that get the support of the median voter
o Does’t predit he the etrees are agaist the oderates
His theory
x Unidimensional policy space
o Space can change with each new proposal (policy space associated with Obamacare is going to
look different from the policy space of the Farm Bill)
x All players (for each time he runs this simulation) are going to have an ideal point on the space
x Only two procedures matter – the two super-majoritarian procedures – the presidential veto and the
Senate filibuster
o Veto can be overridden by a 2/3rd majority by either chamber
o Filibuster (Rule 22) – 3/5th required to invoke cloture
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