In the civilized world, a movement or a demonstration can be effective in bringing about change if it has two qualities: a real grievance that others can sympathize with and nonviolent.

During the civil-rights movement of the 1960s, America saw fire hoses and dogs unleashed on peaceful African-American protesters in Birmingham, Alabama. In his acceptance speech of the Nobel Peace Prize, Martin Luther King Jr. preached, “After contemplation I conclude that … nonviolence is the answer to the crucial political and moral question of our time — the need for man to overcome oppression and violence without resorting to violence and oppression.”

The message was powerful, and the country responded.

Last week, as I was walking down the Cleary Walkway to class, I noticed a group of peaceful demonstrators locking arms in a square. As I was forced to walk around them, I saw that they had their mouths duct-taped and they were holding signs that read, “Black Voices are Not Heard” and “Black Voices Matter.” I thought about this throughout the day.

I thought about this as I went to see Daymond John, an articulate and successful African-American businessman, at the IMU. I thought about this as I heard attendees line up and ask him questions, most of whom were African Americans. I thought about this as I tuned into the news that day and saw the first African American president congratulate the first African American female attorney general, who was confirmed that day. I thought about this as I recalled an email in my inbox from the President’s Black Student Advisory Committee. I thought about this as I remembered the highly publicized “Being Black at Iowa” event in February.

By the end of the day, I had reached a firm conclusion: Black voices are heard at Iowa.

I wrote to the organizers of the demonstration to gauge their concerns, but they did not respond for comment.

On the other hand, the circumstances in Baltimore do demonstrate that there may have been a legitimate grievance. Freddie Gray was arrested and videotapes show that he was unable to walk. A half hour later when he arrived at the police station, he was suffering from injuries that killed him.

Although there are now reports emerging that suggest he may have tried to hurt himself in the vehicle, the refusal of the police to comment for weeks raises serious concerns. In due time, the whole story will come out, and we will know what really happened.

The riots that followed were not only egregious, but they were counterproductive to the entire movement. If we expect Gray to be innocent until proven guilty, why were the Baltimore cops not treated the same way? Instead, violent thugs attacked police and destroyed property. More than 20 officers were injured, and nearly 150 cars burned. The images of the destruction are hard to look at.

For many people, the Baltimore riots took the country’s sympathy away from Gray and turned it into disgust with the rioters.

If a civil-rights movement or a demonstration is to be effective in America, others must be able to understand it and commiserate with the cause. Acts of violence will only divert attention away from the issue, even if they are only orchestrated by a small proportion of the group. It is only because King’s movement had these conditions that he was able to bring real change to fruition.