Edexcel A-Level Politics 9PL0 · Paper 3 USA · Content area 6 of 6

6. Comparative theories

rational theory · cultural theory · structural theory · applying them to the US-UK comparison.
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6.1 Rational theory

Essential Explaining politics through individuals' rational choices.

The specification
6.1Theoretical approaches
Key terminology - tick the terms you can define:
Rational: This approach focuses on individuals within a political system. A rational approach suggests that such individuals will act rationally, choosing to act in a particular way as it will give them a beneficial outcome.

Wording above is the Pearson specification, unchanged. Tick a line only when you could answer a question on it without notes.

Past questions - how it has been examined
  • Partially: the comparative element runs through the US-UK questions (e.g. 2020 Q1b).
  • Also asked (2023 on): 2023 Mock Q2 (holding presidents and PMs to account).
What examiners reward and penalise
  • Stronger: apply rational choice to real behaviour (re-election, bargaining).
  • Weaker: define the theory without applying it.
One way to get high marks
  • Credited: rational theory explains strategic behaviour but misses culture and structure.
  • Evidence: rational theory and congressional re-election.

Where the theories earn their marks. Q2 is compulsory and must be answered through the comparative theories. It is marked on AO1 and AO2 only, 6 marks each, with no AO3. The 2025 examiner guidance is encouraging: one developed comparative point plus one well-explained theory can reach Level 4. The theory must be woven into the comparison, not added at the end of a point: name it, apply it to the specific US-UK difference, and say what it explains.

In the 30-mark essays. The three theories are also your sharpest AO2 tools in Section C: framing an argument through rational, cultural or structural explanations is what "perceptive analysis" looks like to an examiner.

Full official mark schemes for every Paper 3 US question, year by year: open the Paper 3 US mark scheme viewer.

Arguments and counter-arguments

Does rational theory best explain US politics?

Yes

  • Point. Rational theory says political actors calculate what is in their own interest. Explanation. On this view, behaviour is strategic: people choose whichever course of action gives them the best outcome. Example. Members of Congress chase re-election, shaping how they vote and behave around what their voters want. Evaluation. However, culture and rules also shape choices, so calculation is not the whole story.

No

  • Point. Values and institutions matter as much as individual self-interest. Explanation. Not all political behaviour is calculation: people also act on their beliefs and within the rules of the system. Example. Gun culture and the constitution both shape US politics in ways that self-interest alone cannot explain. Evaluation. Even so, rational choice still explains much of the strategy politicians use.
Best judgement. Rational theory powerfully explains strategic behaviour, but it works best combined with the cultural and structural approaches.
Using it in essays
  • Use as a theory in the comparative questions.
  • Evaluation line: "Rational choice explains the strategy, but not the values or rules behind it."
Wider context
Helpful context

Rational theory pairs with cultural and structural theory; the best answers use all three.

Examination priority

Essential One of the three required approaches.

A concrete US-UK pairing

Members of Congress fear primary defeat (Liz Cheney, 2022) while UK MPs fear losing the whip (Johnson expelled 21 Conservative rebels in 2019): both are rational responses to different career threats. In the US your primary voters decide your future; in the UK the party leadership does.

Popularity into power: a rational contrast

A personally popular leader converts popularity into action more easily in the UK than in the US. A PM with a Commons majority can turn a mandate straight into law; a president, however popular, still faces a Congress whose members make their own rational calculation about re-election at home. Same asset, different pay-off, because the rules of the game differ.

6.2 Cultural theory

Essential Explaining politics through shared values.

The specification
6.1Theoretical approaches
Key terminology - tick the terms you can define:
Cultural: This approach focuses on groups within a political system - this could be voters, parties, pressure groups and so on. A cultural approach suggests that the shared ideas, beliefs and values of these groups often determine the actions of individuals within them.

Wording above is the Pearson specification, unchanged. Tick a line only when you could answer a question on it without notes.

Past questions - how it has been examined
  • Partially: the US-UK comparison (e.g. why PM and President differ, 2020 Q1b).
What examiners reward and penalise
  • Stronger: use value-based contrasts (individualism, religious belief, gun culture).
  • Weaker: treat culture as vague.
One way to get high marks
  • Credited: cultural theory explains deep US-UK differences but is hard to measure.
  • Evidence: cultural theory and US individualism; cultural theory and gun culture.

Where the theories earn their marks. Q2 is compulsory and must be answered through the comparative theories. It is marked on AO1 and AO2 only, 6 marks each, with no AO3. The 2025 examiner guidance is encouraging: one developed comparative point plus one well-explained theory can reach Level 4. The theory must be woven into the comparison, not added at the end of a point: name it, apply it to the specific US-UK difference, and say what it explains.

In the 30-mark essays. The three theories are also your sharpest AO2 tools in Section C: framing an argument through rational, cultural or structural explanations is what "perceptive analysis" looks like to an examiner.

Full official mark schemes for every Paper 3 US question, year by year: open the Paper 3 US mark scheme viewer.

Arguments and counter-arguments

Does culture best explain US-UK differences?

Yes

  • Point. Shared values run deep in any political system. Explanation. Those values shape both the policies governments pursue and the parties voters support. Example. American individualism and religious belief mark US politics out from UK politics. Evaluation. The weakness is that culture is hard to measure precisely.

No

  • Point. Institutions matter more than values in explaining US-UK differences. Explanation. The structure of a political system channels how the people inside it behave. Example. The constitution sets the rules that US politicians must work within. Evaluation. In practice culture and structure interact, so neither explanation works alone.
Best judgement. Cultural theory captures value-driven differences the other approaches miss, but it is strongest when combined with structural explanation.
Using it in essays
  • Use as a theory in the comparison.
  • Evaluation line: "Culture explains why the US and UK differ in values, not just in rules."
Wider context
Helpful context

Gun culture (the Second Amendment) is the clearest cultural example.

Examination priority

Essential One of the three required approaches.

A concrete US-UK pairing

After Dunblane (1996) the UK banned handguns within a year, while US mass shootings rarely produce federal laws because the Second Amendment sits inside a deeper gun culture. The same kind of event meets two different value systems and produces opposite outcomes.

Parties before people: a cultural contrast

The UK has a stronger whip culture and a tradition of voting for parties rather than people: most voters back a party label and expect MPs to follow the whip. US politics is candidate-centred - primaries, personal fundraising and personal brands - so members answer to their own voters first. The difference is cultural before it is institutional.

6.3 Structural theory

Essential Explaining politics through institutions and rules.

The specification
6.1Theoretical approaches
Key terminology - tick the terms you can define:
Structural: This approach focuses on the institutions in a political system and the processes within them. A structural approach suggests that political outcomes are largely determined by the formal processes laid out within a political system.

Wording above is the Pearson specification, unchanged. Tick a line only when you could answer a question on it without notes.

Past questions - how it has been examined
  • Partially: the institutional comparisons (courts, constitution, federalism).
  • Also asked (2023 on): 2023 Q2 (US and UK constitutions); 2024 Q2 (UK devolution against US federalism); 2025 Q2 (the constitutions again).
What examiners reward and penalise
  • Stronger: link outcomes to institutional design.
  • Weaker: ignore individual agency entirely.
One way to get high marks
  • Credited: structural theory explains the US-UK contrast (codified vs flexible, separated vs fused).
  • Evidence: structural theory and the codified constitution; structural theory and federalism.

Where the theories earn their marks. Q2 is compulsory and must be answered through the comparative theories. It is marked on AO1 and AO2 only, 6 marks each, with no AO3. The 2025 examiner guidance is encouraging: one developed comparative point plus one well-explained theory can reach Level 4. The theory must be woven into the comparison, not added at the end of a point: name it, apply it to the specific US-UK difference, and say what it explains.

In the 30-mark essays. The three theories are also your sharpest AO2 tools in Section C: framing an argument through rational, cultural or structural explanations is what "perceptive analysis" looks like to an examiner.

Full official mark schemes for every Paper 3 US question, year by year: open the Paper 3 US mark scheme viewer.

Arguments and counter-arguments

Does structure best explain US-UK differences?

Yes

  • Point. The rules of a political system shape how the people within it behave. Explanation. Structural theory explains why US politics suffers gridlock and why its courts are so powerful. Example. The US separation of powers contrasts with the UK's fusion of powers. Evaluation. The danger is that structural theory can downplay the choices individuals make for themselves.

No

  • Point. Culture and individual choice matter alongside the rules. Explanation. Political actors are not just prisoners of the rules: they bring their own values and make their own decisions. Example. Shared values and personal strategy both drive behaviour in ways the rules alone cannot explain. Evaluation. Even so, structure still sets the field of play on which those choices are made.
Best judgement. Structural theory explains much of the US-UK contrast through institutions, but it is strongest alongside rational and cultural explanation.
Using it in essays
  • Use as a theory for institutional comparisons.
  • Evaluation line: "Different structures produce different politics, even with similar values."
Wider context
Helpful context

Structural theory best explains why the US Court and PM differ from their UK counterparts.

Examination priority

Essential One of the three required approaches.

6.4 Applying the approaches to the US-UK comparison

Essential Using all three theories together.

The specification
6.2.1Compare and debate the UK and US Constitutions
Key terminology - tick the terms you can define:
their nature (codified/uncodified) and their sources, provisions and principles, including separation of powers, checks and balances
the similarities and differences between the US federal system and the UK system of devolution.
6.2.2Rational, cultural and structural approaches: Constitutions
Key terminology - tick the terms you can define:
The extent to which rational, cultural and structural approaches can be used to account for these similarities and differences.
6.2.3Compare and debate the UK and US legislative branches
Key terminology - tick the terms you can define:
powers, strengths and weaknesses of each of the Houses
Strengths - I can argue these
Weaknesses - I can argue these
the extent to which each of the Houses are equal.
6.2.4Rational, cultural and structural approaches: Legislatures
Key terminology - tick the terms you can define:
The extent to which rational, cultural and structural approaches can be used to account for these similarities and differences.
6.2.5Compare and debate the UK and US executive branches
Key terminology - tick the terms you can define:
key similarities and differences between the role and powers of the US President and the UK Prime Minister and their impact on politics and government
extent of accountability to the US and UK legislature.
6.2.6Rational, cultural and structural approaches: Executives
Key terminology - tick the terms you can define:
The extent to which rational, cultural and structural approaches can be used to account for these similarities and differences.
6.2.7Compare and debate the UK and US Supreme Courts and civil rights
Key terminology - tick the terms you can define:
basis for and relative extent for their powers
relative independence of the Supreme Court in the US and UK
effectiveness of the protection of rights in each country
effectiveness of interest groups in the protection of civil rights in the USA and the UK.
6.2.8Rational, cultural and structural approaches: Supreme Courts
Key terminology - tick the terms you can define:
The extent to which rational, cultural and structural approaches can be used to account for these similarities and differences.
6.2.9Compare and debate the UK and US democracy and participation
Key terminology - tick the terms you can define:
the different nature of the party systems (two-party and multi-party)
degree of internal unity within parties
the policy profiles of the two main parties in each country
debates around campaign finance and party funding
the relative power, methods and influence of pressure groups.
6.2.10Rational, cultural and structural approaches: Democracy and participation
Key terminology - tick the terms you can define:
The extent to which rational, cultural and structural approaches can be used to account for these similarities and differences.

Wording above is the Pearson specification, unchanged. Tick a line only when you could answer a question on it without notes.

Past questions - how it has been examined
  • Directly: 2020 Q1b (why the powers of the PM and President differ).
  • Partially: every comparative question.
  • Also asked (2023 on): 2023 Q2 (US and UK constitutions); 2023 Mock Q2 (holding presidents and PMs to account); 2024 Q2 (UK devolution against US federalism); 2025 Q2 (the constitutions again).
What examiners reward and penalise
  • Stronger: combine the approaches and reach a judgement.
  • Weaker: use only one approach or none.
One way to get high marks
  • Credited: each approach explains part of the picture.
  • Evidence: comparing the US and UK Supreme Courts.

Where the theories earn their marks. Q2 is compulsory and must be answered through the comparative theories. It is marked on AO1 and AO2 only, 6 marks each, with no AO3. The 2025 examiner guidance is encouraging: one developed comparative point plus one well-explained theory can reach Level 4. The theory must be woven into the comparison, not added at the end of a point: name it, apply it to the specific US-UK difference, and say what it explains.

In the 30-mark essays. The three theories are also your sharpest AO2 tools in Section C: framing an argument through rational, cultural or structural explanations is what "perceptive analysis" looks like to an examiner.

Full official mark schemes for every Paper 3 US question, year by year: open the Paper 3 US mark scheme viewer.

Arguments and counter-arguments

Which approach best explains US-UK differences?

Structural leads

  • Point. It is the two countries' institutions that diverge most. Explanation. Structural theory therefore explains the biggest US-UK contrasts. Example. The codified US constitution stands against the UK's flexible one. Evaluation. On its own, though, this approach misses values and strategy.

Culture/rational add

  • Point. Values and individual choices matter too. Explanation. Cultural and rational explanations fill the gaps that structural theory leaves. Example. American individualism and the drive for re-election both shape US politics. Evaluation. These approaches are less able to explain the headline contrasts between the two systems.
Best judgement. Structural theory explains the largest US-UK contrasts, but the strongest answers blend it with cultural and rational explanation, since each captures a different layer.
Using it in essays
  • 12-mark: why the powers of the PM and President differ.
  • Topic sentence: "The US-UK contrast is best explained structurally, with culture and rational choice filling the gaps."
Wider context
Helpful context

This subsection is the synoptic glue tying the US paper's comparison together.

Examination priority

Essential The comparison is the heart of the US paper.

Similarities and differences at a glance: constitutions
DifferenceThe US constitution is entrenched and codified; the UK's is uncodified and unentrenched.
DifferenceThe UK relies far more on conventions, such as collective responsibility and the Salisbury convention; the US works from a written text.
DifferenceThe US is far harder to amend: only 27 amendments since 1787, while the UK changes its constitution by simple Act of Parliament.
DifferenceFederalism gives US states power by right; UK devolution is asymmetric and granted - and alterable - by Westminster.
DifferenceSovereignty is federal in the US, shared between nation and states; the UK is a unitary state with sovereignty held by Parliament.
SimilarityBoth build in accountability and checks and balances on those who hold power.
SimilarityBoth underpin representative democracy through regular elections.
SimilarityBoth protect rights and rest on the rule of law.
Similarities and differences at a glance: legislative branches
DifferenceThe Senate is the House's legislative equal; the Commons dominates the Lords, which can only delay.
DifferenceThe Senate is elected; the Lords is appointed.
DifferenceCongress can override a veto with two-thirds majorities in both chambers; a PM with a working majority almost never loses a vote in the first place.
DifferencePMQs and the Liaison Committee question the PM directly and in person; Congress cannot compel a president to testify before it.
DifferenceOverall, Congress is the more powerful legislature, while Parliament is the more executive-dominated one.
SimilarityBoth are bicameral.
SimilarityBoth lower chambers are directly elected (the House and the Commons).
SimilarityBoth need executive cooperation to legislate: a programme stalls without the president's signature or the government's backing.
SimilarityBoth suffer deadlock: government shutdowns in the US; hung parliaments and the Brexit deadlock of 2017-19 in the UK.
Similarities and differences at a glance: executives
DifferenceThe President is directly elected for a fixed four-year term; the PM holds office only as leader of the largest Commons party.
DifferenceThe President is head of state and head of government; the UK splits the roles between monarch and PM.
DifferenceThe US cabinet is appointed from outside the legislature; the UK cabinet is drawn from inside it.
DifferenceThe President nominates Supreme Court justices, vetoes bills and issues pardons - powers no PM holds.
SimilarityBoth act as chief diplomat, leading foreign policy and representing the country abroad.
SimilarityBoth lead increasingly personalised politics, with campaigns and media built around the leader.
SimilarityBoth are the chief executive, setting the policy agenda for the government.
Similarities and differences at a glance: Supreme Courts and rights
DifferenceUS justices are politically appointed by the President and confirmed by the Senate; UK justices are chosen by an independent selection commission.
DifferenceThe US court enforces a codified constitution as higher law and can strike down statutes; under parliamentary sovereignty the UK Supreme Court cannot, and can only declare legislation incompatible under the Human Rights Act.
DifferenceUS rights are entrenched in the constitutional text; UK rights rest on statute law that Parliament can amend.
SimilarityBoth courts are independent of the other branches.
SimilarityBoth protect rights against government overreach.
SimilarityBoth are increasingly drawn into political controversy: the prorogation ruling (2019) in the UK, Dobbs (2022) in the US.
SimilarityBoth reason through precedent.
Similarities and differences at a glance: democracy and participation
DifferenceThe US has a strict two-party system; the UK has two main parties plus real minor parties (the SNP, the Liberal Democrats, Reform UK).
DifferenceUS parties are more internally fragmented, with factions that openly fight their own leadership.
DifferenceUS politics runs on far more money and depends on private fundraising; UK campaigns are short and spending is capped.
DifferenceParty discipline is weak in the US and strong in the UK: compare Paxton ousting Senator Cornyn through a primary (2026) with the control the whips exert over MPs.
DifferenceUS interest groups have more access points, with direct lobbying and funding roles, including iron triangle networks linking groups, committees and agencies.
SimilarityIn both countries the practical reality is two parties of government.
SimilarityBoth have seen a rise in populism: Trump in the US, Reform UK in the UK.
SimilarityBoth are increasingly shaped by social media campaigning.
Constitutionalism vs pragmatism

One line worth memorising: US politics argues from the text, asking what the Constitution permits; UK politics argues from what works, asking what Parliament can usefully do. That single contrast - constitutionalism against pragmatism - sits behind most of the differences in the tables above.

Map Timeline (interactive roller)
Helpful context

The three comparative approaches, and how to use them.

Roll through the timeline1 / 4
RationalChoice
CulturalValues
StructuralRules
AppliedUS v UK
Rational

Rational approach. Explains behaviour through individuals' self-interested, strategic choices.

Cultural

Cultural approach. Explains politics through shared values and political culture.

Structural

Structural approach. Explains politics through institutions and the rules of the game.

Applied

Applying them. The best US-UK comparisons combine all three, since each explains part of the picture.

Roll up and down: the arrows, scroll or swipe inside the box, the up and down keys, or click a year above.

Diag Diagram: the three comparative theories applied to one question
Q2's hard rule: explain the difference THROUGH a theory Worked example: why is party discipline weaker in the US than the UK? STRUCTURAL Institutions shape behaviour. Separation of powers means the executive cannot discipline the legislature; federalism gives every member a local base. In the UK, fusion of powers makes careers depend on the leadership. Best fit for institutions questions RATIONAL Individuals follow incentives. A member of Congress answers to primary voters and donors, not the whip - rebelling can be the rational re-election move. A UK MP's seat and promotion run through the party, so loyalty pays. Strongest for behaviour questions CULTURAL Shared ideas shape behaviour. American individualism and the anti-party tradition of the Founders make the candidate, not the party, the unit of politics. UK culture treats the manifesto and the party label as the contract. Strongest for values questions How to use them in Q2 Pick ONE theory and weave it through every point - a bolted-on theory sentence at the end scores little. No theory at all caps the answer at Level 3. The same three theories explain any US-UK difference: constitutions, parties, courts, federalism against devolution.

Exam use: learn the worked example, then swap the middle sentences for whatever Q2 asks. Naming the theory and weaving one integrated explanation through the answer is the Level 4 move the 2025 examiner report rewarded.

Plan Where the essays come from

Each row takes a comparison the specification names, quoted word for word, and shows the 12-mark comparative question it tends to become. Every answer must use at least one comparative theory, so learn the theory line with the question.

The spec wordingThe question this becomesThe two sides in one line
"Compare and debate the UK and US Constitutions"Analyse the differences between the US and UK constitutions.Structural: codified, entrenched rules make US politics court-centred and rigid. Cultural: the UK's flexible constitution rests on shared norms rather than rules.
"Compare and debate the UK and US legislative branches"Analyse the differences between the powers of Congress and the UK Parliament.Structural: separated institutions give Congress an independence Parliament lacks. Rational: MPs follow the whips because their careers depend on the party; members of Congress do not.
"Compare and debate the UK and US executive branches"Analyse the differences between the powers of the US president and the UK prime minister.Structural: a prime minister with a majority commands the legislature; a president must bargain with his. Cultural: expectations of collective cabinet government still bind a prime minister more than a president.
"Compare and debate the UK and US Supreme Courts and civil rights"Analyse the differences between the US and UK Supreme Courts.Structural: entrenchment lets the US Court strike down laws the UK Court must apply. Rational: US justices serve for life, so presidents invest heavily in choosing them.
"Compare and debate the UK and US democracy and participation"Analyse the differences between campaign finance in the USA and party funding in the UK.Structural: First Amendment rulings block the spending limits that UK law imposes. Cultural: UK political culture treats big money in campaigns with a suspicion US politics has lost.
Sum Section summary - the must-knows
1Facts most worth memorising
  • The three approaches are rational, cultural and structural.
  • Rational theory: individuals make self-interested, strategic choices.
  • Cultural theory: shared values and political culture shape behaviour.
  • Structural theory: institutions and rules shape behaviour.
  • Each approach explains part of the picture.
  • Rational theory suits strategic behaviour (e.g. re-election).
  • Cultural theory suits value-based differences (e.g. gun culture).
  • Structural theory suits institutional differences (e.g. the constitution).
  • The approaches frame the US-UK comparison across the topics.
  • The best answers combine all three.
2Examples most worth memorising
  • Rational theory and congressional re-election
  • Cultural theory and US individualism
  • Structural theory and the codified constitution
  • Cultural theory and gun culture
  • Structural theory and federalism
  • Rational theory and presidential bargaining
  • Structural theory and separation of powers
  • Comparing the US and UK Supreme Courts
3Evaluation points most worth memorising
  • Each approach captures part of the explanation.
  • Rational theory can miss culture and institutions.
  • Cultural theory is real but hard to measure.
  • Structural theory can downplay individual agency.
  • The strongest comparisons combine the three.
4Examiner warnings to act on
  • Use the approaches as tools for comparison, not description.
  • Combine approaches rather than relying on one.
  • Apply them to real US-UK contrasts.
  • Name the approach you are using.
  • Keep the focus on explaining differences.
5Strongest essay arguments
  • Each approach explains a different layer of politics.
  • Rational, cultural and structural factors interact.
  • Structural differences explain much of the US-UK contrast.
  • The best answers blend all three approaches.
Test Section test - 12 questions

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