Why do people line up to come to this country? Why do they build boats from milk cartons to sail here? Why do they trust our diplomats and soldiers in ways true of no other country? It’s because we are a beacon of opportunity and freedom, and also because these foreigners know in their bones that we do things differently from other big powers in history.

One of the things we did was elect a black man whose grandfather was a Muslim as our president . after being hit on Sept. 11, 2001, by Muslim extremists. And one of the things we do we did on Tuesday: We published what appears to be an unblinking examination and exposition of how we tortured prisoners and suspected terrorists after 9/11. I’m glad we published it.

It may endanger captured Americans in the future. That is not to be taken lightly. But this act of self-examination is not only what keeps our society as a whole healthy, it’s what keeps us a model that others want to emulate, partner with and immigrate to . which is a different, but vital, source of our security as well.

We’ve been here before. In wartime, civil liberties are often curtailed and abused, and then later restored. Lincoln suspended the writ of habeas corpus during the Civil War. During World War II, we imprisoned more than 127,000 American citizens solely because they were of Japanese ancestry. Fear does that.

Fear after 9/11 was equally corrosive. I have sympathy for people who were charged with defending the nation’s security after that surprise attack. It was impossible to know what was coming next . for which they would be held accountable. But it is hard to read the summaries of the Senate Intelligence Committee’s report and not conclude that some officials and the C.I.A. took the slack we cut them after 9/11 . motivated by the fear of another attack . and used it in ways, and long past the emergency moment, that not only involved torture, but abuse of institutions and lying to the public and other departments of government. If not exposed and checked, such actions could damage our society as much as a terrorist attack.

The Times had amazing coverage of this report, as did others. I came across an interactive feature on washingtonpost.com that distilled charges in the report in a way that turns your stomach.

It said: “Click a statement below for a summary of the findings,” offering a grim laundry list of links to the report’s torture conclusions: “not an effective means of acquiring intelligence,” “rested on inaccurate claims of their effectiveness,” “brutal and far worse than the C.I.A. represented,” “conditions of confinement for C.I.A. detainees were harsher,” “repeatedly provided inaccurate information,” “actively avoided or impeded congressional oversight,” “impeded effective White House oversight” ... “coercive interrogation techniques that had not been approved,” “rarely reprimanded or held personnel accountable,” “ignored numerous internal critiques, criticisms, and objections,” “inherently unsustainable,” “damaged the United States’ standing in the world.”

And there were more. The list told you that our post-9/11 fears led us to tolerate some terribly aberrant, dishonest and illegal behaviors that needed to be fully exposed, because big lies being tolerated lead to little lies being tolerated lead to institutions and trust being eroded from the inside.

I have no illusions: more terrorists are out there and they want to use the openness of our open society precisely to destroy it. And if there had been another 9/11 after the first 9/11, many Americans would have told the C.I.A. to do whatever it wants, civil liberties be damned. Our sentries who prevented further attacks were protecting our civil liberties as well.

We want to keep attracting to our security services people who will have that sense of duty and vigilance. Our bargain is that we have to let them know we understand their challenge and will let them go to the edge of the law . and in rare, ticking time-bomb emergencies even over it, if justified . to protect us.

But their bargain with us has to be that they will take the slack and trust we give them and not go over that edge out of habit, laziness, convenience, mendacity or misguided theories, and in the face internal protests . all of which damage our country. The report is about how that bargain broke down, and it represents an important step in rebuilding it.

I greatly respect how Senator John McCain put it: “I understand the reasons that governed the decision to resort to these interrogation methods, and I know that those who approved them and those who used them were dedicated to securing justice for the victims of terrorist attacks and to protecting Americans from further harm. ... But I dispute wholeheartedly that it was right for them to use these methods, which this report makes clear were neither in the best interests of justice nor our security nor the ideals we have sacrificed so much blood and treasure to defend.” Even in the worst of times, “we are always Americans, and different, stronger, and better than those who would destroy us.”