What would you say to the America of 2040? That question has just been presented to me by a Connecticut group, which asked me to provide some material for what it will call Time Capsule '90, a collection of messages designed to be opened half a century from now.

The invitation is irresistible; none of us knows for sure what's going to happen next week, but thinking ahead 50 years is a cinch. So, buoyed by the knowledge that I won't be around to hear the catcalls, let's title it . . . An Open Letter to the Future.Dear Futurepersons:

First, let's dispose of the obvious: If the pessimists of my day are right, this whole effort is a futile exercise because there won't be an America in 2040. The planet will long since have been ruined, and the only creatures left to peruse these words will be cockroaches.

But the optimist in me says that the human animal, though undeniably foolish and often wildly self-destructive, will not only survive but may even (as the great 20th century writer William Faulkner believed) prevail.

The customary mode of writing a letter such as this is abject apology. It is fashionable to focus only on our failures, which are certainly numerous: children enter the world with little hope of adequate education or medical care, bigotry in infinite variety resides in too many of our hearts, awful diseases endanger the pursuit of happiness. One hopes that new technology will have helped you reach sensible accommodations, but I hesitate to predict total triumph. Solving problems in the distant future usually seems far easier than it actually turns out to be. A half-century ago, I was taken as a little boy to the New York World's Fair, where one received the impression that by 1990 all traffic headaches would have been solved by the autogyro, a combination car-helicopter that would enable one to soar swiftly away from any highway tie-up. In 1990, alas, it ain't necessarily so; many trips take longer now than they did in 1940.

So I wish you smoother transit in 2040, along with purer air and water. As I write, something quite remarkable has just happened: The collectivist nations of Eastern Europe have been quite dramatically discovering the attractiveness of human freedom, as opposed to rigid government controls.

You'll be much cleverer, of course. A half-century ago, for example, we had virtually no knowledge of the tremendous impact of government monetary policy in shaping the prosperity of human lives; now we are only 90 percent ignorant. Your technical data will be better, and, if you are lucky, so will your techniques.

But even if the world works more efficiently, and nations cooperate in the spirit for which most citizens yearn, I suspect that there will still be a need to look for our greatest triumphs, not to some seductive politician, but within ourselves. It's exciting to think of the wonderful life that could ideally be realized by our grandchildren and great-grandchildren. May you have it and enjoy it - and if I turn out to be utterly wrong about everything you have inherited, don't bother to remind me; I'll be otherwise occupied.

Presciently, Louis Rukeyser