WASHINGTON — I admit it: I hate this campaign. There is no moral high ground. President Obama and Mitt Romney are both splashing about in a swamp of negative ads and personal character attacks that, if hardly unprecedented, seem unusual in that they’re increasingly made by the candidates themselves. Any semblance of a reasoned debate over the nation’s future is fading rapidly.

What we ought to be discussing, among other things, is government’s size and scope. An era has ended. The framework for government’s expansion since 1960 is crumbling. Its central feature was that we got more encompassing government (from food stamps to Medicare to Pell grants) without a parallel increase in tax burdens. In 1960, federal taxes were 17.8 percent of the economy (gross domestic product); in 2007, before the financial crisis, they were 18.5 percent of GDP.

What enabled this something-for-nothing swelling of government were two bits of good fortune: first, economic growth averaged slightly more than 3 percent a year; and second, defense spending declined as a share of the budget — in effect, lower defense spending financed higher social spending. Both these props are now gone.

Even with a full recovery from the Great Recession (hardly guaranteed), economic growth is sinking toward 2 percent annually and, perhaps, less. The main cause is the impending mass retirement of baby-boom workers, which will stunt labor force growth. As for defense, past reductions mean that current cuts don’t create much leeway for other spending. In 1970, defense was 42 percent of federal outlays; in 2011, even with the war in Afghanistan, it was 20 percent.

Combined with the surge of baby-boomer retirees, which will increase Social Security and Medicare spending, these trends have thrown our governmental accounts massively out of balance. There would be huge projected deficits even if there had been no Great Recession. The fact that there was adds complexity, because overzealous cuts might imperil the feeble recovery.

One reason that Obama and Romney have resorted to personal attacks is that the political alternatives seem much worse. To discuss the real issues facing the country risks an exercise in voter fury and resentment. Whose spending and benefits should be cut? Whose taxes should be increased? It’s impossible to close long-term deficits simply by taxing the rich and cutting defense (liberal dogma) or eliminating “waste” and “unneeded” spending (conservative dogma).

Other campaign strategies seem equally unpromising. Obama can’t run on his record, because his record isn’t strong. The number of jobs is 4.8 million below the pre-recession peak; the Affordable Care Act (aka, Obamacare) — his singular legislative achievement — isn’t popular, disliked by 44 percent of the public and liked by only 38 percent in the latest Kaiser Family Foundation survey. For his part, Romney seems incapable of summoning a compelling vision for America. He’s campaigning mostly on Obama fatigue.

It can be objected: The candidates are trying to win; they’re not conducting a civics class; it has always been thus. Writing in the Wilson Quarterly, historian Gil Troy of McGill University notes that the “aspects of the campaigns that Americans hate reflect the democracy we love.”

There never was a “mythic golden age” of campaigns, Troy says. As they became more democratic, they also grew less informative. Not until 1840 did presidential candidates campaign; William Henry Harrison appeared at rallies to rebut charges he was a “caged simpleton.” In the 19th century, election days “were mass carnivals, capping months of squabbling, pamphleteering, parading, speechifying, [and] mudslinging.” Today’s campaign is part “carnival and part obnoxious reality TV show.”

Still, Troy argues: “America’s presidential campaign process works. It sifts through candidates, facilitates a continent-wide conversation and, most important, bestows legitimacy on the winner.”

Up to a point, this is convincing. The grueling, prolonged campaign reveals character, values, temperament and political competence —the ability to connect with people, to respond to unanticipated events and to exert leadership — in a haphazard but effective way. Yet there are legitimate doubts as to how well the current campaign will serve its most important role after anointing a victor: conferring legitimacy.

Ideally, campaigns should help prepare public opinion for desirable or inevitable changes. The “conversation” being conducted by Obama and Romney is so far removed from actual economic and budgetary realities that millions of Americans will feel misled.

The rancor that both candidates peddle will make post-election governing harder. The intensifying viciousness might make the winners more arrogant and the losers more angry. And barring an unlikely blowout — with one party controlling the White House, the Senate and the House — winners and losers might straddle the partisan divide.

So that’s why I hate this campaign. When it’s over, we might well be worse off as a nation than when it began.

Robert Samuelson is a columnist with the Washington Post Writers Group.