When will we see reason on nuclear weapons?

Last week Parliament debated the Trident nuclear "deterrent."

There are two sides in this debate - those locked in the permafrost of cold war thinking and those who hope for a better, safer world.

The prospects for an all-out nuclear war have declined from the dangerous 1980s, when as EP Thompson said there were enough nukes around to eliminate humanity 57 times over and the fingers on the nuclear buttons belonged to Soviet leader Yuri Andropov, on a life-support machine and virtually dead from the neck down, and US president Ronald Reagan who was dead from the neck up.

But the likelihood of a nuclear war does not come from design. It comes from accidents.

The world is changing. Four titans of US foreign policy - Henry Kissinger, George Shultz, William Perry and Sam Nunn - have called for an Earth free of nuclear weapons. So has President Barack Obama.

This should give new momentum to the disarmament cause. We are the future on this.

I have often asked ministers to give a plausible future scenario in which nuclear weapons could be used independently by Britain. There is no such scenario.

But ministers in government seem blind to what becomes monumentally obvious as soon as they are out of office.

Former defence secretary Michael Portillo recently said Trident was "past its sell-by date," admitting it was "neither independent, nor any kind of deterrent because we face enemies like the Taliban and al-Qaida, who cannot be deterred by nuclear weapons."

Former prime minister Tony Blair noted in his memoirs of Trident: "The expense is huge and the utility ... non-existent in terms of military use."

Before last week's debate I met a former MP and said we were going to debate Trident. "That was the most difficult decision," he told me, noting that it had needed a whip holding him in an arm-lock to get him into the lobby to vote for it - and the whip himself had told him he didn't believe in it either.

Way back in 1968 a British foreign minister was urging the United Nations to sign up to the new Non-Proliferation Treaty (NPT), arguing that it would be necessary to "follow the treaty up quickly with further disarmament measures."

That was 45 years ago. There was hope then of a non-nuclear world. Is there hope now?

Perhaps. Even Prime Minister David Cameron may have an epiphany. Last October he said: "If we are to have a nuclear deterrent it makes sense to ensure we have something that is credible and believable."

Well, Trident is neither credible nor believable. It undermines our credentials on non-proliferation, the best hope for a safe future. Its replacement should be cancelled. How can we turn to other countries and say: "You can't have nuclear weapons but we're insisting on ours?"

This is part of the mindset that our country is somehow very special. The 19th-century view of empire, that we are powerful and we determine world peace. This is very damaging and we see it in the way that we have to join in every war that comes along.

The continued possession of nuclear weapons of mass destruction has a pernicious effect on our society too. Resources that could have been invested in medical research or hospital beds, education or the environment, are squandered on high-tech killing machines.

The government's recent response to the Scottish affairs committee report Terminating Trident - Days or Decades? stated that the nuclear "deterrent" was "the bedrock of our national security."

Not a bedrock but shifting sands into which our economy is inexorably sinking.

To some, Trident is a virility status symbol. To others it is a comfort blanket. The foreign secretary of the day will say we need it so Britain can punch above its weight.

Punching above our weight means spending beyond our interests and dying beyond our responsibilities.

• Paul Flynn is Labour MP for Newport West. This article is adapted from his speech in Parliament last week.