The rumors that spread shortly after 9/11 have been passed on so often that people no longer know where or when they first heard them. At this point, they have heard them so often, even on television, that they think they must be true.

Image Many in Cairo see the attacks as part of an anti-Muslim plot. Credit... Justin Lane for The New York Times

First among these is that Jews did not go to work at the World Trade Center on that day. Asked how Jews might have been notified to stay home, or how they kept it a secret from co-workers, people here wave off the questions because they clash with their bedrock conviction that Jews are behind many of their troubles and that Western Jews will go to any length to protect Israel.

“Why is it that on 9/11, the Jews didn’t go to work in the building,” said Ahmed Saied, 25, who works in Cairo as a driver for a lawyer. “Everybody knows this. I saw it on TV, and a lot of people talk about this.”

Zein al-Abdin, 42, an electrician, who was drinking tea and chain-smoking cheap Cleopatra cigarettes in Al Shahat, a cafe in Bulaq, grew more and more animated as he laid out his thinking about what happened on Sept. 11.

“What matters is we think it was an attack against Arabs,” he said of the passenger planes crashing into American targets. “Why is it that they never caught him, bin Laden? How can they not know where he is when they know everything? They don’t catch him because he hasn’t done it. What happened in Iraq confirms that it has nothing to do with bin Laden or Qaeda. They went against Arabs and against Islam to serve Israel, that’s why.”

There is a reason so many people here talk with casual certainty  and no embarrassment  about the United States attacking itself to have a reason to go after Arabs and help Israel. It is a reflection of how they view government leaders, not just in Washington, but here in Egypt and throughout the Middle East. They do not believe them. The state-owned media are also distrusted. Therefore, they think that if the government is insisting that bin Laden was behind it, he must not have been.

“Mubarak says whatever the Americans want him to say, and he’s lying for them, of course,” Mr. Ibrahim said of Hosni Mubarak, Egypt’s president.