The protesters, Mr. Mokbel argued, are the ones defending the rule of law, standing up for their right to peaceful expression. With no personal gain, he said, they risk their lives for their cause, for one another, and for their many friends who have fallen. “We owe them something,” he said. “Not just a better economic situation, a government that deals with the people, that is not authoritarian or repressive.”

Mr. Mokbel may be among the more articulate protesters. In the on-again, off-again battles with the riot police near Tahrir Square, the combatants are usually teenagers or even children who appear to live much of the time in the streets. Many seem animated by the sport of it, and ill-informed about the politics.

But Mr. Mokbel, part of an older network of activists that is the backbone of the protests, praised the street children for their energy.

“The street kids are the ones who have suffered the most at the hands of the police, and their demands are much lower — some dignity, respect from the police, a little better life economically,” he said. “They are just releasing their anger.”

Although he acknowledged that some among the demonstrators inevitably provoke the riot police with stones or gas bombs, he nonetheless argued that police aggression caused all the fighting. “Police attacking protesters is what causes the chaos,” he said.

Though a few police officers in other cities have been killed by gunfire, the protesters in Cairo have never been armed. Unlike the bullets and batons of the riot police, Mr. Mokbel argued, the protesters’ rock-throwing was mostly harmless against their opponents’ armor, helmets, and shields.

“Even from the Molotov cocktails, not a single police officer has died,” Mr. Mokbel said. “We do not want to burn down a place that we will end up paying to rebuild.”