Coalition Coalition GovernanceGovernance

The BeginningThe Beginning

Austen-Smith and Banks, Austen-Smith and Banks, 19881988

M: “Predictions of electoral behavior in a multiparty setting M: “Predictions of electoral behavior in a multiparty setting should be a function of voters’ beliefs about how parties will should be a function of voters’ beliefs about how parties will perform following an election. Similarly, party behavior in a perform following an election. Similarly, party behavior in a legislature should be of function of electoral promises and legislature should be of function of electoral promises and rewards.”rewards.”

NH: Voters in multiparty PR do not condition their voting NH: Voters in multiparty PR do not condition their voting choices on party performance after the election.choices on party performance after the election.

P: P: Multistage game Multistage game Terminal node reached by party bargainingTerminal node reached by party bargaining Party influence proportional to legislative seats won in electionParty influence proportional to legislative seats won in election Three parties with no entryThree parties with no entry Voters backwards induct and vote on preferences induced by Voters backwards induct and vote on preferences induced by

bargaining game solutionbargaining game solution Policy outcome is weighted average of party positions in resulting Policy outcome is weighted average of party positions in resulting

coalitioncoalition The equilibrium concept is sequential equilibriumThe equilibrium concept is sequential equilibrium Voters may cast strategic votesVoters may cast strategic votes

Austen-Smith and Banks, Austen-Smith and Banks, 19881988

C:C: If no party wins a majority of seats in the If no party wins a majority of seats in the

election, the equilibrium outcome will consist of election, the equilibrium outcome will consist of a coalition between the largest and smallest a coalition between the largest and smallest partyparty

Party positions in the election are two parties Party positions in the election are two parties symmetrically about the median with third symmetrically about the median with third party at the medianparty at the median

Median party gets fewest votes (but is always in Median party gets fewest votes (but is always in the winning coalition)the winning coalition)

Pre-voting expectation is the median, but the Pre-voting expectation is the median, but the outcome is a coalition between one off median outcome is a coalition between one off median and one median party, hence with a policy and one median party, hence with a policy outcome off medianoutcome off median

Austen-Smith and Banks, Austen-Smith and Banks, 19881988

Grofman, 1985Grofman, 1985 M: Downs has been misinterpreted as M: Downs has been misinterpreted as

having a model per chapter rather than a having a model per chapter rather than a unified theoryunified theory

NH: Voters accept policy promises, in NH: Voters accept policy promises, in spatial models, rather than calculate what spatial models, rather than calculate what parties might actually accomplish in office.parties might actually accomplish in office.

P:P: Unidimensional spatial model in all respects Unidimensional spatial model in all respects

save onesave one Parties can only change the status quo part Parties can only change the status quo part

way toward what they (say they) would like to way toward what they (say they) would like to achieveachieve

Grofman, 1985Grofman, 1985

C: Voters may support the farther C: Voters may support the farther removed party, for that reason.removed party, for that reason.

Grofman, 1985Grofman, 1985