A man sits on a bicycle in front of a line of police officers in riot gear ahead of a 10 p.m. curfew in the wake of Monday's riots following the funeral for Freddie Gray, Tuesday, April 28, 2015, in Baltimore. (AP Photo/David Goldman) (David Goldman/AP)

Danielle Allen is a political theorist at the Institute of Advanced Study and a contributing columnist for The Post.

“Freedom’s just another word for nothing left to lose.” So rasped the great Janis Joplin in 1971, another age of social protest. This thought can help make sense of the Baltimore riots (note: I am not talking about protests). The young rioters we catch glimpses of in photos tweeted out of the smoke have nothing left to lose.

Comparisons have been drawn to the unrest that followed the verdict in the 1992 Rodney King police brutality trial. But the fact is that steep increases in income inequality and mass incarceration, as well as racial disparities in school discipline that start in preschool, mean that the prospects of young African American men are worse now than they were then.

That’s why finding our way out of the riots will require sloughing off the libertarian conception of freedom that has dominated our discourse for a half-century and replacing it with a democratic one. The former is an ideal of freedom as non-interference, the latter one of non-domination.

In his brilliant new book, “Just Freedom,” Princeton philosopher Philip Pettit explains freedom from domination with reference to the expression “free rein.” If you give a horse free rein, it may be able to go where it wants, but the rider retains “reserve control” and can reassert constraint at any point. Or consider Nora in Henrik Ibsen’s play, “A Doll’s House.” Nora’s husband, Torvald, a late-19th-century bourgeois gentleman, applies few restrictions to his wife, who is able to spend her time as she pleases. And yet she’s unhappy. She is at liberty thanks only to his good graces; she is dominated by his reserve control.

To have freedom from domination requires more than just protection of the basic liberty to choose your religion, political party, associations and employment. It also requires an equal share of control over the institutions — the laws, policies, procedures — that necessarily interfere with your life but that do so, ideally, only to protect each individual from domination by another, and any group from domination by other groups.

Libertarian conceptions of freedom, in contrast, define liberty simply as the absence of restraint and originate in the political thought of the utilitarians Jeremy Bentham and John Stuart Mill. Instead of desiring a society where citizens work together to establish the governing framework for their interactions, the 19th-century utilitarians argued for maximizing the number of social relationships organized on the basis of free contracts between consenting adults. Freedom as non-interference, Pettit writes, is the freedom not “to act under any constraints other than those you had negotiated contractually.”

This libertarian concept of freedom seeks a “natural liberty,” while the democratic understanding of freedom pursues “civic liberty.” The goal of libertarian natural liberty is to live with the minimum impingement of law and social norms. Under civic liberty, however, you help create the laws and norms of your society, and these, Pettit says, “promote your freedom in the sense of providing the security that it requires.” Democracy, thus, is “nothing more and nothing less than a community organized around these ideas of equality before and equality over the law.”

Freedom, then, is just another word for true equality.

Pettit offers three simple tests for assessing whether freedom from domination exists in a society: the straight-talk test, the tough-luck test and the eyeball test.

Can the people and their representatives speak forthrightly to one another and to other citizens, or do some find themselves bowing and scraping, for instance, to those with deep pockets? If the latter, domination does exist.

If your side loses a vote in a political dispute, do you have good reason to view it as tough luck, rather than as the “sign of a malign will working against you or your kind”? If you do not, again there is domination.

And, finally, can citizens look others in the eye “without reason for fear or deference”?

This last test resonates powerfully with recent events in Baltimore. We don’t know yet how Freddie Gray suffered a fatal spinal cord injury while in police custody, but we have been told that the encounter with law enforcement began after he made eye contact with a police officer and fled.

This was not Gray’s first interaction with the law. Between 1992 and 1996, Freddie and his sisters tested above the state’s legal threshold for lead poisoning multiple times. It took his mother nearly 20 years to gain legal recourse against the landlord responsible for the peeling paint. That’s the civil side. On the criminal side, beginning in 2007, he had multiple convictions on nonviolent drug charges — possession, intent to distribute and the like.

Pettit’s definition of freedom as non-domination gives us a way to think about Gray’s reaction to police last month. He writes: “Think of what it is to have no physical or legal recourse against an uncontrolled or arbitrary presence in your life.” What do you do if you make eye contact with such an uncontrolled and arbitrary presence? You run, if you cannot hide.

Or you throw the rider. That’s what it means to riot. But what’s necessary is to take the reins: to channel frustration into organized political action, to join the protesters and activists. The desire for freedom from interference devalues government and so does not inspire the pursuit of civic empowerment. Achieving freedom from domination begins with pursuing civic empowerment.

Here’s the thing to remember: Love of the rule of law is fundamentally linked to equality both before and over the law. Can we rebuild our policy frameworks at municipal, state and national levels around the idea that true freedom is the same thing as genuine equality? Doing so is part and parcel of restoring the rule of law.