After Major James Abbott's poetry, the White House changing all its tunes and al-Qaeda's melodramatic confirmation of its leader's death ("We will remain, God willing, a curse chasing the Americans and their agents, following them outside and inside their countries" - can a curse chase, let alone outside and inside?), does America finally have closure? The notion has certainly been bandied about.

On learning that Osama Bin Laden's body had been slipped into the sea, the press decreed that a line had been drawn under 11 September 2001. Then President Obama visited Ground Zero and laid a wreath - an act, according to his spokesman, "to perhaps help New Yorkers and Americans everywhere to achieve a sense of closure". Time to move on, he seemed to say; this horrible event has been exploited long enough.

Closure is a very American word: it demands an American accent - the curl of that "r" at the end. An LA therapist comes to mind, called something like Dr Zog, treating semi-neurotic agents and actresses, and deeply neurotic waitresses who wish they were actresses and sleep with their agents. Zog sits in an air-conditioned beige office, wearing a Nehru suit, his hands arched in mock-prayer. "And would you say, Ms Lohan," Dr Zog asks with all the sincerity of a monk, "that you have achieved closure?"

What does it mean, though? We understand it as an imagined door shutting on the past, a movement forward. Gestalt theory describes the law of closure as the way that the mind will self-organise to complete an unfinished form; we naturally join the dots. The word is a child of "enclosure", from the Old French closture, a "division, hedge, wall, fence", which stems from the Latin clausura, "lock, fortress, a closing". These are physical things, barriers to protect or separate you from something on the other side.

Surely, this is all closure can ever be - a view-blocker, a flimsy screen. As any teenager who has ever liberally applied cover-up to a spot can tell you, just because you can't see something doesn't mean it's not there. (Or does it? Insert wide-ranging philosophical discussion here.) l