Back in January, 2002, when George W. Bush’s war on terror was getting into full swing, Terry Jones, a British comedian who was part of the Monty Python troupe, asked an awkward question: “How do you wage war on an abstract noun? It’s rather like bombing murder.” Eleven years later, nobody has come up with a convincing answer, perhaps because there isn’t one. But in the past couple of days, we’ve seen some laudable efforts to reframe the question in a manner that’s more amenable to rational discourse.

I’ll get to President Obama’s speech about resetting U.S. policy in a moment, but he wasn’t the only politician who spoke yesterday about combating terrorism. In London, David Cameron, the British Prime Minister, delivered a commendably measured response to the brutal murder of an off-duty British soldier outside an Army barracks in Woolwich, south London. After paying tribute to the victim, Lee Rigby, a twenty-six-year-old private who had served in Afghanistan, and issuing the standard declaration that Britain “will never give in to terror,” Cameron noted that the attack, carried out with kitchen knives and meat cleavers, “was also a betrayal of Islam—and of the Muslim communities who are give so much to our country. There is nothing in Islam that justifies this truly dreadful act.” Cameron went on:

We will defeat violent extremism by standing together, backing our police and security services, and, above all, by challenging the poisonous narrative of extremism on which this violence feeds.

He ended the speech thus: “The police have responded with heightened security and activity—and that is right. But one of the best ways of defeating terrorism is to go about our normal lives. And that is what we shall all do.”

Quite possibly, Cameron’s tone had something to do with the British yen for adopting a pose of sang-froid toward anything short of a nuclear attack. But, like Obama, he was also trying to come to terms with reality. In Woolwich, as in Boston last month, the attacks, heinous as they were, appear to be have been petty plots cooked up by disaffected local youths who had turned to radical Islam but who had little or no contact with organized terrorist groups, such as Al Qaeda. While such attacks can succeed in spreading terror, they pose no significant threat to the state. In what sense, then, can they justify putting (or keeping) the country on a permanent state of war footing?

This was one of the questions that Obama addressed in his speech at the National Defense University on Thursday, which has rightly received positive reviews, including one from my colleague Jane Mayer. Noting that America has so far expended more than a trillion dollars and seven thousand lives in the open-ended conflict that Bush began, he called on Congress to amend its 2001 authorization for the use of military force, which gave the President broad latitude to engage in counterterrorism operations anywhere in the world.

Commentators and human-rights groups have rightly noted that a speech is only a speech. Will the new guidelines for drones attacks make much of a difference in how they are carried out? Will Guantánamo be closed? Will the Justice Department continue to subpeona reporters’ phone records in search of national-security leaks? It will take some time for the answers to emerge. But Obama’s speech shouldn’t be judged solely on how its individual recommendations are carried out—its contribution was broader. It didn’t just question the utility of individual measures, such as holding prisoners without trial, it queried the intellectual underpinnings of the whole war-on-terror enterprise, the entire mindset that has gripped the country for the past eleven and a half years.

Such a questioning was long overdue. Civil liberties aren’t the only liberties that the war on terror has abridged. Equally pernicious has been its encroachment on intellectual liberty. Ever since 9/11, the mere mention of Al Qaeda, or the general threat of radical Islam, has often been sufficient to suspend sensible debate about all sorts of questions. In an era of fiscal retrenchment, does it make sense to spend taxpayer’s money on ever-more elaborate airport scanners, or on Alzheimer’s research? What’s the bigger threat to the United States, a splintered Al Qaeda or a revival of tensions between China and Japan? Should the rebuilt World Trade Center be converted into a semi-militarized security zone? Such questions are rarely even discussed, outside of a few rarified think tanks and editorial boards.

Part of the problem goes back to the conceptual issue that Terry Jones identified back in 2002: If you go to war with “terrorism” or “terror,” how will you know when you’ve won?

With most wars, you can say you’ve won when the other side is either all dead or surrenders. But how is terrorism going to surrender? It’s hard for abstract nouns to surrender. In fact it’s very hard for abstract nouns to do anything at all of their own volition—even trained philologists can’t negotiate with them… The bitter semantic truth is that you can’t win against these sort of words—unless, I suppose, you get them thrown out of the Oxford English Dictionary.

Obama didn’t endorse that particular idea. Instead, he suggested restricting the definition of terrorism to something narrower and more manageable: “Beyond Afghanistan, we must define our effort not as a boundless ‘global war on terror’ but rather as a series of persistent, targeted efforts to dismantle specific networks of violent extremists that threaten America.” That sounds sensible, as does his admission that “neither I, nor any President, can promise the total defeat of terror. We will never erase the evil that lies in the hearts of some human beings, nor stamp out every danger to our open society.”

The attacks in Boston and Woolwich illustrated that, of course, and, given the resentments (some justified, some fantastical) that exist in the Muslim world, there are likely to be more of them in the future. At least for now, though, our leaders are making some of the right noises, which is important. As Obama said, “We must define the nature and scope of this struggle, or else it will define us.”

Above: David Cameron. Photograph by Alastair Grant/AP.