In an interview with CNN yesterday, outgoing FBI director Robert Mueller offered up words one could characterize as defending mass surveillance of all Americans’ phone calling. Indeed his interview has been portrayed as a defense of such spying, with outlets like NRO’s “The Corner” reporting “Outgoing FBI Chief: ‘Good Chance’ NSA Would Have Prevented ‘Part’ of 9/11.” But Director Mueller spoke much more equivocally than that.

Here’s what he actually said.

CNN: If we had the kind of intelligence that we were collecting through the NSA before September 11th, the kind of intelligence collection that we have now, do you think 9/11 would have been prevented?

MUELLER: I think there’s a good chance we would have prevented at least a part of 9/11. In other words, there were four planes. There were almost 20 — 19 persons involved. I think we would have had a much better chance of identifying those individuals who were contemplating that attack.

CNN: By this mass collection of information?

MUELLER: By the various programs that have been put in place since then. … It’s both the programs (under the Patriot Act) but also the ability to share the information that has made such dramatic change in our ability to identify and stop plots.

Mueller vaguely cited “various programs,” giving them a retroactive chance of preventing “a part of 9/11.” But even this defense of post-9/11 powers is insufficient.

In our 2006 paper, “Effective Counterterrorism and the Limited Role of Predictive Data Mining,” IBM scientist Jeff Jonas and I recounted the ease with which 9/11 attackers Khalid al-Mihdhar and Nawaf al-Hazmi could have been found had government investigators pursued them with alacrity. The 9/11 Commission said with respect to al-Mihdhar, “No one was looking for him.” Had they been caught and their associations examined, the 9/11 plot probably could have been rolled up. Sluggish investigation was a permissive factor in the 9/11 attacks, producing tragic results that nobody foresaw.

That absence of foresight is a twin with retrospective assessments like Mueller’s, which fail to account for the fact that nobody knew ahead of 9/11 what devastation might occur. Immediately after the 9/11 attacks, everybody knew what such an attack could cause, and everybody began responding to the problem of terrorism.

Would Patriot Act programs have prevented at least a part of 9/11? Almost certainly not, given pre-9/11 perceptions that terrorism was at the low end of threats to safety and security. A dozen years since 9/11, terrorism is again at the low end of threats to safety and security because of multiplicitous efforts worldwide and among all segments of society. It is not Patriot Act programs and certainly not mass domestic surveillance that make us safe. Even Mueller didn’t defend NSA spying.