6.1 - Rational, cultural and structural approaches

Comparing a shared dimension

A useful comparison asks the same question of both countries before explaining the result.

Suppose the question is how far legislators can frustrate an executive's policy. In the USA, Congress must approve legislation even when the president has won a national electoral mandate. In the UK, ministers usually sit in Parliament and a government normally relies on support in the Commons. Both legislatures can reject proposals; their relationships with the executive differ.

A comparison therefore needs three connected moves: identify a shared feature, give accurate evidence from each country and explain what connects or separates the cases. “The USA has a president; the UK has a prime minister” names offices, but does not yet explain their different control of law-making. A better link is that a president cannot assume a congressional majority, whereas a prime minister normally draws authority from maintaining a Commons majority.

The rational, cultural and structural approaches offer explanations, rather than three additional facts to memorise. They start with different units: individuals, groups and institutions. They can overlap. Party loyalty might reflect a member's career calculation, a shared political commitment and rules governing nomination or confidence. You should explain which mechanism you mean.

Two dated cases make the shared question concrete. On 28 July 2017, the US Senate rejected the proposal known as the Affordable Care Act's “skinny repeal”, 49 votes to 51. On 12 March 2019, the UK Commons rejected Theresa May's Brexit deal, 391 to 242. Both executives faced legislative resistance, despite their different constitutional positions. The votes establish the outcomes; they do not, by themselves, prove why every legislator voted that way. US Senate record, UK Parliament record.

Rational explanations: choices and incentives

A rational explanation examines what an individual expects to gain or lose by choosing a political action.

“Rational” does not mean morally right, perfectly informed or guaranteed to succeed. A politician may misjudge voters and still make a calculated choice. The benefit might be re-election, promotion, protecting a policy commitment or preserving a reputation. Specify the benefit; calling behaviour “self-interested” without explaining the choice adds little.

Apply the approach to the shared dimension of executive control of legislation. A UK government MP might support a bill because defeating their own government could damage its electoral reputation or their prospect of ministerial promotion. A US senator might support a president's agenda to appeal to party voters, but might oppose it if constituents or primary-election challengers make opposition more advantageous. In both countries legislators balance competing audiences. The consequences of their choices differ because a US senator is not voting on whether the president retains parliamentary confidence.

These are plausible causal interpretations, not established private motives. To support one, look for a member's explanation, their constituency interests, candidate-selection pressures or a pattern of votes. Do not assume that a legislator who rebels has ceased to act rationally: the perceived benefit of rebellion may outweigh its cost. Equally, commitment to an idea may matter independently of career advantage.

Cultural explanations: shared commitments

A cultural explanation asks how the beliefs and expectations of a group influence its members' behaviour.