We could do with a little more gloominess in American politics. History suggests we aren’t likely to get it.

Back in 1979, President Jimmy Carter darkly—but to all intents and purposes accurately—divined a “crisis of confidence” stalking the land. Mr. Carter’s “malaise” speech, as it became known, succeeded only in fueling the sense that he didn’t have the stuff of which great presidents were made.

Mr. Carter was ejected from the Oval Office the following year. The man who defeated him, Ronald Reagan, would in due course be nudged toward re-election by a campaign ad commonly referred to as “Morning in America.”

The television spot captured to a tee the sunny optimism that both Mr. Carter and Mr. Reagan’s 1984 opponent, Walter Mondale, lacked. And it mixed in a large dollop of feel-good patriotism for good measure.

The current crop of presidential contenders have absorbed these lessons well. They know a bullish sense of American pride is required of them, and they express it at every opportunity.

The Republicans are, on balance, more jingoistic and determinedly upbeat than their Democratic rivals. But even the Democrats take care to wrap their complaints about the Bush era in overtly patriotic garb. (An Internet search for the leading candidates’ names and the phrase “greatest country in the world” provides ample evidence of how all-pervasive this boosterism has become.)

That’s all well and good. But in the present moment relentless proclamations of America’s greatness run the risk of concealing more than they illuminate. They numb the capacity for self-criticism. They distort the picture of the world and exaggerate the U.S.’s dominance. And they downplay the nation’s problems and push solutions farther out of sight.

The truth of the matter, unpalatable though it may be, is that the U.S.’s recent track record across a range of areas is mediocre. And it is getting worse.

The bridge collapse in Minnesota last week was first and foremost a tragedy for those directly affected. But—like the Manhattan steam pipe explosion that resulted in one death last month—it was also a graphic demonstration of the creakiness of the nation’s infrastructure.

The American Society of Civil Engineers noted two years ago that more than a quarter of the nation’s bridges were either structurally deficient or functionally obsolete.

A report issued three months ago by the Urban Land Institute and Ernst & Young came to stark conclusions.

“The United States’ relatively low investment in virtually all aspects of mobility-related infrastructure—airports, public transit, railway systems, roads and bridges—is an ‘emerging crisis’ that will compromise the ability of the nation’s cities to compete globally,” a press release heralding the report noted.

The authors themselves added: “America is no longer a world leader when it comes to infrastructure.”

The failure to maintain an adequate infrastructure might almost be forgivable if the federal government were committed to frugality. But its stinginess with the upkeep of roads and bridges is more than matched by profligacy in other areas, from the tax cuts that this administration has lavished on wealthy Americans to the innumerable earmarked expenditures for parochial interests that Congress, even under new Democratic leadership, continues to approve.

That spendthrift behavior is part of the reason why the U.S.’s national debt as a proportion of GDP is worse than about three-quarters of the world’s. Major developed nations (Britain, Spain, Australia) as well as minnows (Namibia, Paraguay, Papua New Guinea) best the U.S. in that category.

The picture is depressingly similar in other areas that have an even more intimate connection to quality of life and to America’s capacity to compete internationally.

In education, for example, a major 2006 survey relying on data from the previous few years found that the relatively strong performance of American children in elementary school fell off sharply later. Compared with those of about 30 other industrialized nations, 15-year-old Americans performed significantly worse than average in math and science, and only average in reading.

Then there is the ongoing outrage that is the American health care system. One does not have to be a fan of the demagogic Michael Moore to note the importance of one statistic highlighted in his recent movie, Sicko—that the U.S. ranked a lowly 37th in a World Health Organization comparative survey of health care systems, well below the likes of Colombia, Portugal and Chile.

At least the Democrats argue that something serious must be done about health care. Among the Republicans, knee-jerk jingoism remains the order of the day. Lambasting Democrats’ proposals on health care last week, Rudy Giuliani said:

“We’ve got to do it the American way. The American way is not single-payer, government-controlled anything. That’s a European way of doing something.”

This is not patriotism in the true sense. It is a combination of stubbornness and prejudice. People like Mr. Giuliani insist that the American way is, automatically and eternally, best. Among the many problems with that view is that it forestalls the possibility of borrowing ideas that work elsewhere and using them to improve American lives.

America has an abundance to be proud of in its history. It owned the century just gone. But, contrary to what super-patriots and religious zealots believe, its pre-eminence has never been the result of some celestial blessing; it was the consequence of wise judgments by those in whom the people had vested political power.

American dominance can be ended by bad decisions as rapidly as it was engineered by good ones. Its current trajectory is downward.

Bold policies are required if the trend is to be reversed. But the popular appetite for tough decisions is dulled by endless, star-spangled bluster that underplays the challenges ahead.