Last week, I had troubled thoughts at dead of night. They weren't clever or original or even that severe: just the morbid sort that might have crept up on you too had you been preparing to fly out of Stansted with your wife and some of your kids the day after the latest alleged terror plot arrests. You know the sort of thing. If our plane explodes will we die straight away or only after falling, screaming through the air? Are we really in a third world war?

We arrived at the airport before five in the morning and as I picked my way through the crush of fellow passengers gazing up in hope at flight indicator boards, I was reminded of those images of anxious families huddled on tube station platforms during the Blitz. I felt a kind of reverence for British forbearance under fire. Then the doubts began creeping in.

I mean, we were going to Dublin. Standing in the queue to have my groovy shoes x-rayed, and politely averting my gaze from the tampons nestling loosely in the clear plastic bag of a woman in front of me (as demanded by the leaflets we were given) I reflected that the Irish capital was not a likely choice of non-destination for a suicide bomber taking his last ride. And soon I was loitering next to a pair of armed policemen as my four year-old, wearing her best pink dress, raised her arms in preparation to be frisked.

What exactly was I witnessing? To what extent was this surreal ritual of inconvenience necessary to protect lives from fanatics? How much of it, by contrast, was effectively an imposed, mass-participation public relations exercise designed to "send a message" to the public that the terror threat is grave and that the government is taking it seriously?

I really wish I knew. I'm certain that some mixture of both was involved, and even that such may be justified. I can't be confident, though, of where the balance lies. In other words, when it comes to the "terror threat" in general, I can't decide how cynical I ought to be.

Please don't get the wrong end of my schtick: I'm quite certain there remain Islamists in Britain who dream of murder on a major scale (not to mention everywhere else in the world, with the possible exception of Greenland); not for one loopy second do I think that the alleged terror plot being investigated (partly on my doorstep) at the moment has been all but invented by the authorities purely to shore up faltering public support and justify stealing our civil liberties.

But that's about as far as my certainty goes - which isn't really very far at all. I am, for instance, strongly inclined to disbelieve any rhetoric spouted by that shameless red top-pleaser John Reid, and the frightening thing for Britain is that I doubt this is a minority view. Indeed, such is my disbelief in our government's good faith where security is concerned that I'm quite ready to believe reports here and elsewhere that British security chiefs would sooner have waited for any bomb plot to have unfolded further before making arrests (and thereby strengthened their chances of getting convictions) but went in early because that's what their edgier American counterparts wanted.

In fact it occurs to me that, short of dangerous fantasists' conspiracy theories, the only information I'm not too cynical to believe is that which reflects poorly on the reliability of our government, our spooks or our police. The paradox is that my cynicism about their dire warnings tends to justify my being scared. So I'm scared of the people who think that it's OK to kill me and I'm scared by the ones who keep telling me I should be scared of them. No wonder I'm so sceptical too.

I have a feeling I'm not alone in my confusion. After the first of the recent consecutive false alarms in or above their country, American TV news anchors started getting stick from viewers. Why, they were asked, have you been spending all this time filming a bunch of luggage on the tarmac at Boston airport when it turns out that all that happened was that a nervous middle-aged woman took a pot of hand cream on board? Rowing back from their earlier over-excitement, some presenters began debating whether the episode was a case of the "new normal" - the phrase coined in the wake of 9/11.

In a way, it was: the "new normal" is not knowing either how frightened or how disbelieving to be - and ending up being both at the same time.