For those who live in the shadow of one of the most remarkable states to emerge in world history, the image of the UK now floundering in prolonged indecision over Brexit is shocking.

Decisive rejection of the UK-EU withdrawal agreement in the House of Commons for a third time, following hot on the heels of the House’s rejection of eight alternative approaches, raises uncomfortable questions about the quality of the UK’s decision-making process.

A venerable corpus of political science literature pays tribute to the pragmatism and resilience of the British political system, and its capacity to cope successfully with both domestic challenge and external threat. But why is this system so apparently helpless, and can anything be done to resolve the UK’s ambitions for a new relationship with the EU?

There are three broad areas where modification of British “exceptionalism” might help.

1. The constitution

‘David Cameron won an overall majority in 2015 with just 37% of the overall vote.’ Photograph: Reuters

First, reliance on an “unwritten” constitution is an impressive achievement – if it can be pulled off. Almost all democracies, however, have opted for a formal, relatively inflexible codification of the political ground rules in a national constitution.

For the UK, such a foundation document could provide a durable framework for rectifying glaring defects in contemporary British structures. It could formalise more clearly the relationship between London and the four countries of the UK. It could reconstruct the House of Lords, whose growth appears unstoppable. It could spell out the currently ambiguous relationship between government and parliament.

In particular, it could modernise the capricious 19th-century electoral system that unfailingly reproduces an unrepresentative House of Commons. The two most recent general elections illustrate this formula’s political perversity. David Cameron won an overall majority in 2015 with just 37% of the overall vote, hardly a popular mandate for Conservative rule. But Theresa May’s critical loss of this majority in 2017 took place despite an increase in the Conservative vote to 42%.

2. Political culture

‘The opposition opposes.’ Labour leader Jeremy Corbyn.

Photograph: UK Parliament/Jessica Taylor/PA

Second, critics of the “Westminster model” of government commonly cite its adversarial style as an impediment to problem-solving. Its inbuilt majoritarianism may offer a useful mechanism for resolving most issues. The government’s parliamentary majority and the whip system normally ensure passage of all measures, and in principle facilitate coherent policy formation. The opposition “opposes”, biding its time until the mercurial electoral system brings it back to power.

This “winner takes all” system may function well while there is regular government-opposition alternation and the stakes are relatively low. But it can be corrosive when (as in Northern Ireland from 1921 to 1972) there is no such alternation, or when (as in the case of Brexit) the stakes are very high.

The case for a more inclusive deliberative process in matters of vital national importance is irresistible. Constitutional conventions, cross-party forums and citizens’ assemblies have supplemented parliament in other jurisdictions in tackling particularly sensitive and sometimes quite fundamental policy matters. Such devices might surely help to purchase wider agreement on the form Brexit should take, even if full consensus proves unattainable.

3. Geopolitical perspectives

‘The UK possesses substantial military clout.’ An RAF helicopter collects troops from the RN ship RFA Lyme Bay. Photograph: SAC Chris Thompson-Watts RAF

Third, the criticism that many leading Brexiteers are insufficiently familiar with EU structures and procedures carries weight, but it may be that they also misperceive Britain’s place in the contemporary world.

Early hubris about the ease with which the UK could go it alone and complete attractive trade deals across the globe has diminished, but many appear still to overestimate the UK’s negotiating position. The post-imperial military, diplomatic and economic resources of the UK are formidable, but they are now challenged by the growing power of its European neighbours.

True, the UK has a large population, is the fifth-largest economy in the world and possesses substantial military clout. But its share of the EU population is only 13%, its share of nominal GDP is 15% and its military personnel account for 13% of the EU total.

Put differently, when negotiators on behalf of the EU27 face their British counterparts, they speak for a bloc that is six to seven times more substantial than the UK in these areas. This is hardly a contest of equals.

It would surely be unwise for the UK to embark on a programme of constitutional reform in the middle of its Brexit odyssey. But it would help to view the Brexit process from a different perspective, challenging if not reversing certain currently dominant assumptions.

The very constitutional flexibility that permitted the UK to hold a consultative referendum has also permitted this to be retrospectively interpreted as a binding plebiscite. The hidden, unfortunate dictum that it is “the opposition’s duty to oppose” has compromised the capacity of the main parties to seek out common ground. The deceptive image of British potency has invited the use of dangerous implicit threats against the much more powerful EU27 bloc.

Recognising that there is nothing sacrosanct about a consultative referendum, that government and opposition need not be deadly enemies and that the UK is by far the weaker player in the Brexit negotiations may be a big cultural challenge. But it is surely not an insurmountable one for the country which, while maintaining many of its own archaic procedures, exported democracy to much of the rest of the world. Might it not also facilitate a more productive outcome to the UK’s negotiations with the EU?

• John Coakley is a professor in the School of History, Anthropology, Philosophy and Politics at Queen’s University Belfast, and a fellow of the Geary Institute, University College Dublin