The front page of The Inquirer on Tuesday nicely framed the journey we have taken since the attacks on Sept. 11, 2001.

The picture at the center of the page showed workers bolting in place "The Last Column," the final support structure left standing after the World Trade Center towers were reduced to smoking piles. It will now stand as a permanent display at the site's memorial museum.

On the same front page, the headline on the lead story read, "U.S. to probe CIA tactics on suspects," and reported that the Obama administration has decided to open a criminal investigation into the severe tactics used by some interrogators questioning captured terrorists.

The use of the word suspects in the headline reflects our confusion over how to fight an organization like al-Qaeda. Are its captured operatives criminals awaiting trial or enemy soldiers with valuable intelligence? Is our primary interest prosecution, or national defense?

I will predict right here that the investigation ordered last week by Attorney General Eric H. Holder Jr. will not result in prosecuting CIA agents or any top officials of the Bush administration. If the investigation uncovers a clearly rogue interrogator guilty of some murderous outrage, that's one thing, but those who were working under close supervision from Washington, complying with their instructions, no matter how outrageous some believe them to be, will not be charged with crimes. Ordering the investigation will please those on the left who are more angry than most Americans about harsh interrogation methods, and they may shed further light on whether such tactics worked - early indications are that they did.

The use of the word suspect goes right to the heart of the matter. It is a word applied to criminal defendants, who are presumed innocent until proved guilty. A captured enemy soldier has never enjoyed the presumption of innocence, but we are engaged in a struggle that falls somewhere in between conventional war and law enforcement. One thing we have learned is that if a captured terrorist is squeezed to provide critical intelligence, he makes for a problematic criminal defendant. Military commissions have rightly ruled that coerced information cannot be admitted as evidence in the trials of accused terrorists. This underlines the principle that coercion should only be considered in those rare instances where the need for current intelligence outweighs the desire for eventual prosecution.

Holder's announcement last week shows how far the pendulum has swung over the last eight years. When the twin towers were still smoldering and we were getting color-coded threat alarms, few would have objected to hanging al-Qaeda boss Khalid Sheik Mohammed by his thumbs from the Capitol rotunda. Now that such fears have greatly receded, in large part because of the efforts of U.S. soldiers and intelligence agents, at least some citizens are appalled by the idea that CIA interrogators actually frightened captive terrorists during questioning.

National security tends to shoulder aside all other concerns when we feel threatened - think internment camps for Japanese Americans, or, in a coarser age, scalp bounties for Native Americans. When we felt more threatened, the Bush administration brushed aside noble procedural concerns, making the big and entirely predictable mistake of licensing (via questionable legal memos and secret findings) some nasty methods of interrogation. This has always produced widespread abuse, and did so again. To its credit, that administration quietly reversed itself when it realized the damage it had done. Military interrogators working in Iraq and Afghanistan saw an abrupt turnabout after 2004, when the outrages at Abu Ghraib were revealed. Harsh tactics were forbidden, and some of the worst offenders were prosecuted and punished.

How much further do we wish to go in correcting these missteps? It seems clear that CIA interrogators dealing with important captives were being guided at the highest levels of government. These captives ultimately helped explain and unravel al-Qaeda's shadowy international organization. Punishing Republican officials for aggressively reaching, even overreaching, in this effort to protect this country would satisfy certain of Obama's fringe supporters, but would outrage most Americans. It would be one of the most divisive acts in the history of the White House. I don't believe the president will do it, first, because it's the wrong thing to do, and, second, because he is ambitious.

President Obama has said repeatedly that he wants to look forward, not backward, as he takes up our ongoing national defense. Faced with that responsibility, he has already embraced some of the methods condemned by the left - most recently the practice of rendition. Not all of the steps taken by the Bush administration, it seems, were unwarranted and intolerable. Even some of its early mistakes work to our benefit.

It is not a bad thing for a man in an interrogation room to be afraid. Most of those I have met with experience in this ugly business agree that of all inducements to cooperate, fear is the most powerful. Fear is more effective even than pain. All useful interrogation, even the most benign, takes place in a climate of fear. The criminal suspect hopes he will lessen his sentence by cooperating. In most wartime situations an arrested enemy soldier fears, with reason, that he will be summarily shot.

We shouldn't torture captives, and we should never harm their families, but I don't mind their worrying about it. I want them to worry about it. A lot.

I wrote an article for The Atlantic in 2007 called "The Ploy," which told a story of the exceedingly clever interrogations in Iraq that led to pinpointing and killing al-Qaeda leader Abu Musab Zarqawi. No one harmed or directly threatened any of those questioned in that effort, but the key information was ultimately delivered by a man who wished to avoid being shipped to Abu Ghraib.

This was long after the abuses at Abu Ghraib had been curtailed, but he was afraid of the place.

Mark Bowden is a journalist and author, most recently of "The Best Game Ever." E-mail him at mbowden@phillynews.com.