The shadow of George W Bush hovered over last night's debate between Obama and Romney

When, after the second presidential debate, I said that Barack Obama should make better use of his best weapon in this election – George W Bush – I didn’t mean like this. I meant blame America’s economic malaise, which any way is showing signs of improvement, on his predecessor. Instead, the younger Bush inadvertently came to the fore during this campaign last night. A debate focused on foreign-policy revealed an introspective and inward-looking America still very much in the long shadow cast by the Bush Doctrine.

Obama’s aim was to deliver some strong lines, look assertive and experienced, trumpet his successes and gain whatever advantage could be gleaned from an area in which he leads Mitt Romney – though not by much. He succeeded, emerging as the clear winner according to a bunch of immediate polls as well as common sense. As Nate Silver argues, even a small gain last night could be invaluable given how tight this race is.

Mitt Romney’s aim was to avoiding making any calamitous errors, walk a more moderate path than during his blustering and blowhard campaign, and not lose too much ground in an area of obvious relative weakness for him. He succeeded, emerging as a clear loser but not fatally so.

A debate in which both participants succeed in fulfilling their chief ambitions is very unlikely to be electorally decisive. Last night was interesting for another reason: what it told us about America’s course.

Romney alleged that in no region of the world has American influence grown over the past four years. This is myopic. One of the most unquantifiable but precious aspects of Obama’s foreign policy has been his undoing of the reputational harm wrought by Bush. But it shows that declinism is baked into the American psyche.

Later, Romney repeated his astonishingly immature, willy-waving boast about labelling China a currency manipulator from his first day as President. The idea that your first day in the White House should be devoted to sticking two fingers up at your main rival, not so much an emerging but emerged superpower on whom you will increasingly depend, is stupidity. But Romney said it because his private polling suggests this is a popular stance. In other words, it resonates because Americans have become more nationalist and protectionist in their approach to trade, which is both self-harming and a shame.

Except for the final 15 minutes on China, the debate focused almost exclusively on parts of the world where Islam is in the ascendant: Syria, Libya, Afghanistan, Iran. This reflects terribly on the American electorate. Naturally, given the news agenda and the death of so many American soldiers in these places, they had to be covered.

But there are two problems here. First, if you look at the detail, Obama and Romney largely agree on these areas. Romney was at pains, for instance, to move to Obama’s stance on nurturing Syria’s moderate opposition.

And second, it came at the expense of everything else. Even on the subject of Islam, there was no mention of the places where it has made a sceptical friend in democracy, Turkey and Indonesia. And what of the other great global challenges? Climate change, anybody? Mutually prosperous trade with India, Mexico, or Brazil perhaps? Some place called Europe? Or, most morally compelling of all, the vast murder, famine, hunger and potential of sub-Saharan Africa?

None of that. Instead, a debate that never ignited, but will likely lead to a small boost for Obama, proved that the legacy of Bush the younger was even more deleterious and all-encompassing than we imagined.