Look around the world. What appear to be the biggest potential threats?
Strategists worry about the rise of an authoritarian China, a lawless Russia and the threats of new wars in the Middle East or North Korea. Economists highlight the dangers of a trade war. Lawyers point to the Trump administration's "America First" rejection of international treaties. Environmentalists and a growing number of voters insist on the paramount importance of climate change.
Very few people could argue with a straight face that Germany, or moves toward greater European unity, pose the greatest threat — even to Britain. Yet those views were common in the UK 30 years ago. In fact, they provided the intellectual and emotional foundations for the rejection of the EU that culminated in the 2016 vote for Brexit.
The reunification of Germany after the 1989 fall of the Berlin Wall, the creation of a single European currency and talk of political union in Europe, came as a profound shock to Tory Britain in the early 1990s — and it reawakened old fears of German power.
Margaret Thatcher, who was then prime minister, held a seminar with eminent historians, where the assembled company brooded about Germany's historic "aggressiveness, assertiveness, bullying, egotism". Nicholas Ridley, a member of her cabinet, had to resign after giving an interview comparing Chancellor Helmut Kohl of Germany to Adolf Hitler.
The men who have led the charge for Brexit — people like Boris Johnson, Nigel Farage and Michael Gove — were launching into public life in those years and were profoundly shaped by the atmosphere of the time. Appointed as a foreign correspondent in Brussels in 1989, Johnson stoked the Tory tribe's horror of a "federal Europe".
But 30 years later, fears of an imperialist EU led by a revanchist Germany look absurd. These days, Germany is regularly lambasted by its western allies for its pacifism. It is stubbornly resisting demands from Brussels and Paris for deeper economic union. Britain is, in any case, not a member of the EU's most federalising project — the euro.
With fears of German aggression relegated to the history books, where they belong, Brexit's claim to contemporary relevance now rests on the slogan "Global Britain". The thesis is that the EU represents an ever-diminishing share of the global economy. The real growth is coming in Asia and other emerging markets.
So, backers argue, it makes sense for Britain to cut itself loose from a sclerotic Europe, to better pursue global opportunities.
But once again, the analysis is outdated. The prospectus for "Global Britain" is based on a series of optimistic assumptions about the world that were valid in the 1990s and for some years afterwards — but no longer apply.
Global Britain assumes a world that is moving towards free trade, rather than against it; a world in which global finance is confidently expanding; a world in which the US is the anchor of the west, with an unquestionable commitment to Nato; a world in which Russia is flat on its back and China is just a promising emerging market, not an emerging superpower.
None of this is true any more. Instead, Britain faces a world in which international rules are breaking down under the pressure of renewed competition among great powers and a resurgence of protectionism in the US. It is an exceptionally perilous time to launch the Global Britain project.
Nothing better illustrates this problem than the Brexiter insistence that a "no deal Brexit" is perfectly feasible because Britain can simply trade on World Trade Organization rules.
Even if the WTO were in perfect health, this would be questionable — because WTO rules would still entail high tariffs on cars and food, and onerous bureaucracy. But, as it happens, the WTO is in serious trouble because the US is deliberately sabotaging its dispute-settlement mechanism, as part of Trump's assault on the global trading system.
The strain on the WTO will only increase if the US-China trade war intensifies. American tariffs and restrictions on technology exports to China — combined with Chinese retaliation — raise the prospect that the world is moving towards a trading system built around rival blocs. Those blocs could well retreat behind higher tariff walls and restrict technology transfers to outsiders. That makes it the worst possible time for the UK to consider leaving its own preferential trading arrangement — the EU.
If Johnson does become prime minister later this summer, he will swiftly have to focus on these real threats facing modern Britain, rather than the fantasy threats that he helped to conjure up 30 years ago.
Almost all of the modern threats — from a resurgent Russia to climate change and trade wars — are much easier for Britain to deal with, by using the collective strength of the EU. But, absurdly, Johnson's top priority will be to leave the EU.
As a young Brussels correspondent, he marvelled at the sensation that his tales of an imperial EU were creating back in Conservative Britain. Their impact, he later recalled, gave him a "weird sense of power." Now, weirdly, he is likely to taste real power — and to have to deal with the consequences of the fantastic tales that he spun so many years ago.
Written by: Gideon Rachman
© Financial Times