With the Fourth of July barbeques so close we can smell them, America’s attention has turned to thoughts of star-spangled banners and charcoal-grilled beef. But before we shoot off the fireworks, we should pause to reflect upon an anniversary of another sort.

Today marks the 49th anniversary of the passage of the Civil Rights Act of 1964, the legislation that outlawed discrimination on the basis of race, religion, national origin, and sex. It was the landmark achievement of the civil rights movement, the legislative embodiment of Martin Luther King, Jr.’s dream.

Yet, as I have detailed during the last few days, a half century later, a disturbing share of the March on Washington’s objectives have not been achieved. Inequality is as persistent as ever and the United States remains starkly segregated by race. America is still in dreamland.

Maybe instead of a dream, MLK should have had an expectation.

Let me explain. One of the big problems with sticky income distributions – above and beyond the proximate suffering they inflict – is that they lead to sticky thinking. And this is where expectations come into play.

Dreams are about what could happen. Expectations are about what will happen. Dreams are hopes; expectations are beliefs. Every certainty begins as a possibility, and every triumph was once a wish.

It’s hard to overstate the importance of expectations. Apple can earn $13 billion in profits, but if investors were expecting more, its stock will fall. When the Mets make the playoffs New York celebrates; when the Yankees make the playoffs, the manager keeps his job for another week.

And as behavioral economists and psychologists will tell you, it’s easy for expectations to become self-fulfilling prophesies. When consumers fear a recession, the economy actually contracts. When inflation is anticipated, prices rise. Much of what the Fed – or any central bank – does is to race people’s expectations. According to some accounts, the only time monetary policy works is when the public is fooled about changes in prices resulting from changes in the money supply.

Of course, self-fulfilling prophesies aren’t only economic in nature. Students who give up studying for “impossible” tests increase their chances of failure. Youth hockey players identified as prodigies are more likely to make it to the pros. The best drug trials are “double blind” because when either patients or doctors think a treatment will succeed, recovery becomes more likely.

In a similar manner, the death of the American dream can help explain the failure to realize MLK’s. The further poor – and often black – Americans are foreclosed from opportunities for advancement, the less worthwhile striving ahead seems. Each setback becomes a roadblock, and each roadblock, and dead end. Why bother trying if trying won’t help?

Call it the law of diminishing expectations. The less you expect, the less you achieve, and the less you achieve, the even less you come to expect.

Take teen parenting. Often, we view non-martial childbearing as a ticket to poverty. But as Melissa Kearney and Phillip Levine have found, the causality is just as likely to operate in reverse: poor adolescent girls who grow up in unequal environments are less likely to harbor hope for progress and more likely to have babies as unwed teens, partly as psychic substitutes for unachievable material prosperity.

The story is similar with regard to educational and occupational attainment, where socioeconomic status is frequently cited as the strongest determinant of expectations, which, in turn, influence outcomes.

Given their overrepresentation at the socioeconomic distribution’s lower tail, blacks are disproportionately victimized by the law of diminishing expectations. But to conclude there is somehow a racial basis for languishing aspirations – a sort of cultural malaise – would be a dangerous mischaracterization. In fact, after controlling for socioeconomic status, blacks have higher educational and occupational aspirations than their white counterparts.

But the existence of the spurious correlation between race and expectations does give rise to the most insidious type of self-fulfilling prophesy: stereotype threat. First identified by Claude Steele and Joshua Aronson, stereotype threat describes situations in which negative stereotypes impair performances in such a way as to confirm the negative stereotype.

For example, when intelligence inferiority stereotypes are salient, blacks perform worse on standardized tests than whites (even controlling for SAT scores). Similarly, whites perform worse than blacks on motor skill tests when they are presented as measures of natural athleticism.

Applied to the law of diminishing expectations, the very notion of upwardly immobility depresses expectations and, by extension, outcomes.

There is scarcely a human affliction more unsettling than forsaken dreams. Ambition, once abandoned, becomes energy without an outlet, power without a purpose. Relative deprivation is more painful than isolated disadvantage; squalor is underscored when surrounded by splendor. Under these conditions, it’s all too easy for undirected potential to chart iniquity’s course. Striving is replaced by sulking, resolve by resentment. When getting ahead becomes giving up, each disappointment becomes an excuse, and each excuse another reason not to succeed. Few try to fail, but many fail to try.

Americans have never been big fans of equality of results, but we do care passionately about equality of opportunity. At the core of our national identity is the deeply held conviction that if you work hard and play by the rules, you will make it. From John Rockefeller to Jay-Z, rags can become riches. But making that transformation requires determination infused with optimism, self-efficacy blended with trust in the system.

Dr. King had a dream, but dreams can only get us so far. We need results. Without tangible progress, dreams become constraints rather than catalysts, cauldrons of despair rather than beacons of a better life. To achieve, we must believe.

Putting into place dream-affirming policies – like a more progressive tax code, a more compassionate safety net, and a more inclusive educational system – would help. But we can’t ignore America’s crisis in confidence, and we must restore our belief in ourselves – and in our neighbors.

To reach our full promise, we must make good on the promise our Constitution guarantees: that the pursuit of happiness is within our reach.

We simply cannot expect anything less.