THERE is one truth you will never hear spoken this election year. To admit it would guarantee defeat at the hands of a populace that values unfounded optimism more than reasoned pragmatism.

Imagine the political disaster if someone had the courage to say, "This country is in an inevitable decline as a political and economic power. Neither I nor my opponent can stop the process, but I will acknowledge it and attempt to cope." Quicker than you can say "malaise," that candidate would drop twenty points in the polls.

Unfortunately, we can no longer afford to waste our strength in vain attempts to shore up the myths of the past--whether it be assuming superiority to Japan or acting as if our economy could grow indefinitely. We know the facts, but we haven't really faced up to them.

What if the ideal candidate did? He would recognize the following dilemmas:

Our incomes have stagnated for the last fifteen years, despite different administrations, technological advance, the exploitation of resources, and massive borrowing.

Our care systems will soon be overwhelmed by an aging population, thousands of AIDS sufferers, and victims of the pollution that our industrial society has spawned.

Global warming is turning the Great Plains back into the Great American Desert. We've overproduced and overconsumed and left nothing on the land except our own wastes. And to top it off, we have a debt so big that just servicing it sends us deeper into the red.

The last eight years under Reagan have exacerbated the situation, but the Democrats--all of us, really--share the blame, along with economic, ecological, and historical forces nobody could have done much about.

Now it's time to face facts and make the best of a bad job. It will be hard, and taxes will have to be raised even more than is currently being secretly planned in both campaign headquarters. Hopefully, we can distribute the burden fairly.

IF I were running for President (or even dogcatcher), I would have just lost the election. The denial of "eternal progress" and "Fortress America" is that shocking to our psyches.

We could ignore our position, and in twenty-five years, at the outside, we will take a very hard fall. Or, right now, we could begin studying the choices we have; so when we are forced to decide which problems to attack, we will do it in a fully informed and fair way. Four issues immediately come to mind, but they're only a small sample.

First, we must shift our defense to a multilateral partnership with our allies in Europe and East Asia, while we can still do so smoothly. Maintaining the fiction of Pax Americana not only worsens our own situation, it is dangerous for all democracy. We may soon become an unreliable and overextended ally.

Second, we must rebuild a sense of community in this country, so we can rely on our neighbors during the hard times to come. In particular, we need strong and sophisticated local governments. Through higher pay and educational incentives, we can shift our best-trained public servants from the bureaucracies to the communities, where they will be needed most.

Third, we need to streamline and speed the legal system. Unless we can break the logjam in our courts and prisons, any increase in crime (due to the social stress we will surely experience) may undermine the rule of law entirely. If we must sacrifice certain safeguards and privileges, it will be to retain our basic liberties.

Fourth, but hardly finally, we will have to make hard choices in our public care systems. We may have to conduct a national version of triage--limit how much we will spend to save one life and restrict the number of those on public assistance. If we start thinking about this question now, we can make those choices with compassion, rather than desperation.

These hard problems are being ignored because the public is afraid of hearing about them. The candidates pitches are just symptomatic of the public's desires.

Our decline should be an issue of national debate and research, not a dirty secret. When the candidates rhapsodize about the dream of the immigrants, or proudly recite the pledge of allegiance, I remain uninspired. These are no substitutes for making sure that something of that dream remains alive--a dream of freedom and opportunity, not superpower status.