WASHINGTON — The juxtaposition of the Justice Department’s damning Ferguson report and President Obama’s fine speech to mark the 50th anniversary of Bloody Sunday was coincidental. But the founders of the civil rights movement would certainly have found it providential, so I’ll go with that.

The report cleared a man while indicting a system. It describes a patchwork of municipalities that have become predators, trapping residents in a web of tickets, fines, fees and warrants in order to raise revenue. Police officers and municipal judges are employed as collection agents, squeezing citizens on behalf of local officials who want to spend public money without the inconvenience of taxation. And police departments such as Ferguson’s — lacking diversity, proper training and accountability — are prone to swagger and profiling.

This is the elevation of the speed trap into a philosophy of government. Citizens are treated as marks and suckers. And the burdens fall heaviest on those without the resources to game a system that is gaming them. In this atmosphere of exploitation, any racially charged incident — even one in which racial animus can’t be demonstrated — can set spark to tinder.

The details of these practices are important to guide changes in Missouri law. But the situation in Ferguson also reveals something broader: How people who do not regard themselves as biased can be part of a system that inevitably results in bias. How men and women who view themselves as moral can comprise an immoral society.

It is inherently difficult to stand in judgment of a social structure that one is part of. It is hard to see the wheel on which we turn. This requires empathy — the ability to imagine oneself in a different social circumstance; to feel just a bit of the helplessness and anger of someone facing injustice. And it calls upon moral imagination — the capacity to dream of a better future in accord with first principles.

Both empathy and moral imagination are achievements of rhetoric. Some use the adjective “rhetorical” as an epithet — denoting something artificial or manipulative. But there was a reason the civil rights movement set great store by well-crafted words: to reveal the routine cruelty of segregation and to place unfair suffering in the context of a story that gives it purpose. That story is perhaps the most extraordinary outside the Bible: a captive people, by their courage and persistent demands, eventually redeeming the democratic soul of the nation that enslaved them.

Events like the Selma march demonstrate that history is not bunk, or one damn thing after another, or any such cynical rot. One week after Bloody Sunday, America was fortunate to have President Lyndon Johnson provide rhetorical context. “At times, history and fate,” he said, “meet at a single time in a single place to shape a turning point in man’s unending search for freedom.”

And America was fortunate, 50 years after Bloody Sunday, to have Obama appeal to America’s moral imagination. “In one afternoon 50 years ago, so much of our turbulent history — the stain of slavery and anguish of civil war; the yoke of segregation and tyranny of Jim Crow; the death of four little girls in Birmingham, and the dream of a Baptist preacher — all that history met on this bridge. It was not a clash of armies, but a clash of wills; a contest to determine the true meaning of America.”

Obama, for whatever reason, has often been hesitant to provide rhetorical leadership on civil rights. He embodied something he seldom adequately explained. But that can no longer be said after Selma. His speech was skilled in its use of quotation and refrain. But it was remarkable for expressing the creative tension at the heart of the civil rights movement: a set a principles that both ennoble and judge our country — ideals that make it lovable and make it restless.

Obama told a compelling story of genuine but incomplete progress, while expressing a deep confidence in national ideals and character. He embraced “the belief that America is not yet finished, that we are strong enough to be self-critical, that each successive generation can look upon our imperfections and decide that it is in our power to remake this nation to more closely align with our highest ideals.”

This is the reason that, while Ferguson may be our reality, it is not our identity or our destiny. America has a vision of human dignity that stands in perpetual challenge to our fallen practice, leaving us always haunted and always hopeful.