(FORTUNE Magazine) – It was when I first read, some months ago, that a blue-ribbon commission was proposing that the government begin investing a portion of the Social Security trust fund in the stock market that I began to have my doubts about the investing culture we've created in this country. It's not that I'm against investing. (Heaven forbid!) Nor am I opposed to the kind of broad, middle-class investing that has become such a common part of life in America. On the contrary: To my mind, the melding of Wall Street and Main Street has been, by and large, a boon for both. But I have begun to wonder recently whether our emphasis on investing--our astonishing, stubborn faith in it as an all-purpose tonic--isn't likely to lead us astray in some important ways. Truth to tell, I think it already has.

Consider, for starters, what we now expect of the stock market. Not wish for, mind you, or dream about, but expect. We expect that the stock market will send our kids to college. After all, with college costs rising so insistently, what else can we rely on to pay for them? We also expect that the market will provide the multimillion-dollar cushion we'll need to retire on. As pensions have been largely displaced by 401(k) accounts--which is to say, as our employers have shifted the burden of funding our retirement from themselves to us--again, what choice do we have but to count on the stock market? True, the investment industry has done everything in its power to encourage these expectations, but still, we've bought into them wholeheartedly. By now, we even assume that if (perish the thought) we're downsized, our investment portfolio will help tide us over--perhaps even our investment in the company that just laid us off. This once-supreme irony barely raises eyebrows anymore. The thing we now take for granted is that the market will go up forever, and that will take care of everything.

The easy point to be made here is that this is usually what people start believing deep into a bull market--that there inevitably comes a point when the memory of down markets simply evaporates. Fourteen years into the current bull market, we've clearly reached that point. But there's something larger going on too. After all, the 1950s saw its own tremendous bull market, and it was never as it is now. Back then, investors didn't need the market the way we do now. "This is blood money people are putting in the market today," says Peter Bernstein, an economist with an interest in financial market history.

And when you look at it that way, our unquestioning faith in investing is downright scary. Does it make sense to assume that the stock market will always be there to provide those things we view as fundamental to a decent middle-class life? To anyone who can still remember when markets went down as well as up, the answer, plainly, is no. And yet our belief in the market is so unwavering that this is no longer something we even think about. As investment manager William Fleckenstein puts it, "People have confused need with certainty. We need this to work, therefore it will." There are other problems too. As a matter of social policy, is it appropriate to set up a system where the kind of life one gets to lead depends on one's ability to pick stocks? When stated like that, of course, it sounds silly, yet that's the kind of society we're building.

Most of all, though, the bull market has allowed us to paper over serious national problems. A classic example is the disappearance of pensions. It's hard to imagine a national issue of more potential consequence to more people. And yet where has been debate over this enormous change in American life? In fact, there has been no debate. Why? Because we assume that Mr. Market will be there for us, making everything all right in the end.

To me, that's what is so troubling about the proposal to put some of the Social Security trust fund into the stock market. Elsewhere in First, Peter G. Peterson, chairman of the Blackstone Group, lays out a series of reasons he thinks the Social Security idea is a bad one, but I'm more bothered by the psychology behind it. We all know that Social Security is ultimately unsustainable. We also all know that even the slightest hint that Social Security needs to be reformed is political suicide. So rather than face this pressing problem squarely, what do we do instead? We say, Let the stock market fix it.

But it won't fix the problem, because it can't. We're kidding ourselves to believe otherwise. Someday--perhaps sooner than we care to think about--this bull market will end, and the psychology will change. But the problems will still be there, waiting for us to do the hard things that we've been avoiding. The stock market can do many things for us, but it can't save us from ourselves.

REPORTER ASSOCIATES Joyce E. Davis, Ani Hadjian, Lenore Schiff, Lixandra Urresta, Tricia Welsh