Believe the polls, and Americans have decided that they live in Italy: hobbled by dishonest leaders and such endemic corruption that only fools would trust strangers.

Grim findings have been coming thick and fast. Most Americans no longer see President Obama as honest. Half think that he "knowingly lied" to pass Obamacare. Fewer than one in five trust the government in Washington to do what is right. Confidence in Congress has fallen to record lows.

Frankly straining credulity, a mammoth, 107-country poll by Transparency International, a corruption monitor, this summer found Americans more likely than Italians to say that they feel that the police, business and the media are all corrupt.

Americans are also turning on one another. Since 1972, the Chicago-based General Social Survey (GSS) has been asking whether most people can be trusted or whether "you can't be too careful" in daily life. Four decades ago Americans were evenly split. Now almost two-thirds say others cannot be trusted, a record high.

The press is full of headlines about an American crisis of trust. That is too hasty. In genuinely low-trust societies, suspicion blights lives and hobbles economies. In China, even successful urbanites distrust business and government, worrying constantly about the food they buy and the air they breathe.

It is true that America faces grave problems. Congress has had an unproductive year: shutting down the federal government was a notable low point. The Internal Revenue Service confessed to subjecting Tea Party and other political groups to special scrutiny, enraging conservatives. But to put such antics in perspective, this year Italy's richest media tycoon and ex-prime minister, Silvio Berlusconi, was convicted of tax fraud, abuse of power and paying an underage prostitute.

In genuinely low-trust countries, tax evasion comes naturally. But America shows few signs of surging tax evasion. Nor are Americans at soaring risk of being ripped off in daily life. The latest survey of consumer fraud by the Federal Trade Commission found a fall in the prevalence of scams.

None of this justifies complacency. Americans are dangerously angry. But when they voice Italian levels of distrust for authorities, or sweepingly accuse fellow-citizens of being crooks, they are not describing reality.

Here is a theory: Americans are instead revealing how deeply they are divided. Dig into headlines about "half of all Americans" thinking this or that, and large partisan or demographic divides lurk. Take that poll finding that half of voters think Obama lied to pass his health plan. Look more closely, and eight in 10 Republicans think he fibbed, but fewer than one in four Democrats.

Robert Putnam of Harvard University, a pioneer in the study of "social capital," argues that Americans' trust in one another has been declining steadily since the "golden" aftermath of the Second World War, when civic activity and a sense of community among neighbors were at a peak. Trust in institutions has risen and fallen over that same postwar period in line with external events, plunging after the Watergate scandal, for instance, and during recessions.

Yet something new seems to be happening. Anti-government cynicism is feeding on gulfs in society.

Conservatives think Democrats buy votes with welfare. Consider the crisis around Obamacare. Forget fussing about its useless website; websites can be fixed. The president's headache is that voters see his plan as welfare for the poor rather than a better way of delivering medical care. That is exposing ugly divisions. Most starkly, a majority of whites think the law will make life worse for them, a National Journal poll found, while most nonwhites believe it will help people like them. That in turn tallies with a big change over the previous 15 years: a collapse in support among conservatives for government safety nets.

This is America's real problem with trust. The country faces a crisis of mutual resentment, masquerading as a general collapse in national morale. Sharply delineated voter blocs are alarmingly willing to believe that rival groups are up to no good or taking more than their fair share.

Polls describing America as a hellhole of corruption are not to be taken literally. They are a warning. America is not a low-trust society. But it risks becoming one.