Questions: Party Organization and Internal Party Discipline

Question 1

A backbench MP in a Westminster parliament defects from the governing party on a major budget vote, causing the government to lose. What institutional feature makes such defections so much rarer in Westminster systems than equivalent defections in the US Congress?

• A. Westminster MPs are more ideologically loyal to their parties than US legislators tend to be
• B. Westminster parties can expel members from parliament without a democratic vote
• C. A lost confidence vote can trigger the dissolution of parliament and new elections, putting the defecting MP's own seat at risk
• D. Westminster MPs receive higher salaries and committee stipends that create stronger financial incentives for compliance

Answer: (C)

The structural mechanism is government survival through confidence: a failed major vote can bring down the government and trigger elections in which the defecting MP may lose their seat. This creates an overwhelming incentive for loyalty that has nothing to do with ideology (A), formal expulsion authority (B), or compensation (D). In the US Congressional system, votes cannot bring down the executive, so defection carries far lower institutional stakes. The same politician placed in each institutional context would likely behave differently — the structure drives the behavior.

Question 2

A country switches from a single-member district electoral system to proportional representation with closed party lists, where voters choose parties and leaders rank candidates. What is the most direct consequence for party discipline?

• A. Discipline weakens because more parties enter the system and coalition-building fractures each party's internal cohesion
• B. Discipline strengthens because candidates' electoral survival now depends on their ranking by party leaders rather than their individual vote share
• C. Discipline remains essentially unchanged because legislators' ideological positions do not change with the electoral system
• D. Discipline weakens because voters become more informed and hold individual legislators accountable for their votes

Answer: (B)

Closed party lists give leadership direct leverage over candidates: a legislator who defects risks being ranked lower on the list at the next election, reducing their chance of winning a seat. This is a structural shift that changes incentives regardless of ideology. Option A conflates party system fragmentation with intra-party discipline — more parties doesn't mean less discipline within each party. Option C ignores how institutional change reshapes incentives. Option D has the causal direction backwards.

Question 3

The higher level of party discipline observed in Westminster parliaments compared to the US Congress is better explained by institutional design than by differences in politicians' personal commitment to their parties.

• T. True
• F. False

Answer: True

Both systems contain ideologically motivated politicians, but the institutional structures create radically different incentive environments. Westminster systems tie individual political survival to party unity through confidence mechanisms and leadership control of candidate selection. The US system allows legislators to build independent political brands and imposes no institutional penalty for defection — it can even be electorally beneficial. The same politician placed in each system would likely exhibit different behavior, which is the hallmark of a structural rather than dispositional explanation.

Question 4

American Congressional parties have consistently maintained weak internal discipline across most periods because the US federal structure prevents central party coordination.

• T. True
• F. False

Answer: False

The qualifier 'consistently' makes this false. Polarization in recent decades has dramatically increased party-line voting in Congress even without structural changes in electoral rules. As the two parties have become more ideologically homogeneous — with fewer conservative Democrats and liberal Republicans — the cost of defection from the party line has risen, and cross-party coalitions have become rarer. Discipline is not a fixed property of a party system but responds to shifting conditions, including the ideological composition of the parties.

Question 5

What is the principal-agent problem in party politics, and how do Westminster systems resolve it in ways that US-style congressional systems do not?

Model answer: The principal-agent problem arises because party leadership (principal) wants legislators (agents) to vote with the party, but legislators have their own constituencies, convictions, and career interests that may diverge from leadership preferences. Westminster systems resolve this by dramatically raising the cost of defection: losing a confidence vote can bring down the government and trigger elections in which the defecting legislator risks their own seat. Leadership also typically controls candidate selection (party list rankings or local candidate approval), giving them direct power over whether legislators can even appear on the ballot. The US system leaves both mechanisms weak — Congressional votes cannot topple the executive, and primary elections allow candidates to build bases independent of national party organizations — so defection carries low institutional cost and may be electorally advantageous.

The analytical move is to understand discipline as a solution to a structural incentive problem, not as an expression of loyalty. This means party discipline can be deliberately designed — or weakened — by changing electoral rules, government formation rules, and candidate selection procedures.