Unidimensional spatial model

Stewart, Chapter 1

Plan of presentation

• Why do we care about theory or explanation at all?

• History of studying Congress

• Politics of Lineland

I.Why do we care about theory or explanation at all?

•That’s what social scientists do

•That’s what politicians do

•That’s what citizens do

•Think about the current campaign and ideological polarization

Different professions have different ways of theorizing about legislatures

•Activists: good guys and bad guys

•Reporters: individual stories about good guys and bad guys

•Political scientists: The general, generic, and predictable

II.Brief history of political science

• Early days ~ 1880 “formalism”

• ~1900 to 1950: Progressivism

• 1950-1980 “Sociology”

• 1980 to present: “Economics”

What are they?

• Formalism: understand Congress by the written rules.

• Progressivism: understand Congress by comparing to normative standards

• Sociology:– The group is what is important– Congress is a group, made up of other groups

• Economics– The individual is what is important– Collective behavior derives from individual interests,

preferences, and behaviors

Congress and intelligence reform

• Formalist:– What does the Constitution say about the role of Congress and the

Executive in intelligence?• Progressive:

– Does the Constitution actually govern the exercise of intelligence?– Is intelligence gathering a war making power?

• Sociology– Who are the actors? What (social) roles do they play?– What factors constrain the actors to stay within their roles (e.g. what is

the committee environment)?• Economics

– Who are the relevant actors, what are their goals (election, power, policy)

– What are the strategic moves that the individuals make in order to optimize over the policy space?

Advancements in legislative studies

• Our understanding of legislatures has become more precise over time

• Modern legislative analysis focuses on the interaction between individuals and institutions– Without institutions, decision making is chaotic– Heritability problem

• Theoretical primitives– Preferences– Rules

Logic of this style of analysis

•Begin with simple preferences

•How does decisionmakingproceed without institutions?

•How does decisionmakingproceed withinstitution?

•Add complexity and stir

The politics of lineland

• Think of the world as a single dimensional policy space

• Harold Hotellings “grocery store” problem

• Downsian model of competition: converge on the median voter– No matter the shape of the

underlying distribution!

WalMart

Target

C1 C2

More formally …

• We care about:– Preferences– Alternatives– Rules

Preferences

•Dimensionality (1,2,many)

•Location and characteristics of preferences

–Ideal points

–Utility curves

Different curves

Alternatives

• Plain English: motions, amendments, etc.• Expressed in same coordinate system as

preferences• Heresthetics (Riker): The art/science of trying

to alter the dimensionality of a policy debate– Clinton impeachment (private sex vs. perjury)– 9/11-related detainees (civil liberties vs. security)– Framing of Bush/Kerry campaign

“Framing” in Bush/Kerry Campaign

The importance of the reversion point or status quo

• The point where we end up if nothing happens. It is an outcome.

• The most important alternative• Taxing vs. spending: may have different reversion points• E.g. Public schools in Pacific N.W.

Rules Matter

Majo rity requ iremen tSimp le or su perma jority?

Age nda s ettingWhic h altern atives and in which o rder?

Pure majority rule: do es it ev er happ en?Exa mple: Olesze k pg. 2 31 (6 th editio n)

The median voter theorem drives this analysis

• IF– The issue is unidimensional– Voters decide based on their preferences– Preferences are single-peaked– Voting proceeds under pure majority rule

• THEN – The median voter’s ideal point will prevail– Or the median is the dictator

Reminders: symmetry does not matter, only single peakedness

Example of a lack of a single peak

The politics of flat land

A

B

C

SQ

Pc(SQ)

PB(SQ)PA(SQ)

Ic(SQ)

Who was the median voter in Congress in 2003?