Sometimes, I feel like I'm taking crazy pills. I seem to be one of the only people who has noticed that amid the biggest financial crisis in a generation, parliament has just insouciantly waved through £350 million on some drawings of some new submarines. Maybe I'm being unfair - maybe there will also be scale models to sit on an admiral's desk too, maybe even a Troy Tempest uniform for Nick Clegg to dress up in - but it still seems like a hell of a lot of money.

Of course, this £350 million quid is just a down-payment - the start of the whole bloated nightmare of the hooting defence procurement panjandrum. Now that we've paid out £350 million quid on sci-fi submarine drawings, any attempt to now withdraw from this commitment will be met with a round chorus of boos and hisses about wasted money.

There is almost literally no political debate on this issue, which I find astounding. I mean, I understand why, in narrow, party political terms.

Ed Miliband has to burnish his manly credentials and appear "tough on defence" - particularly vital in a Labour leader who you can't imagine doing anything other than begging for his life if left alone in a room with Vladimir Putin. Cameron, on the other hand, can't cut a button or bayonet or a badge from the military without fear of a ferocious coup from the crusty neo-UKIP wing of the Tory right, most of whom would not be out of place as the villain in a Sharpe novel.

In the coalition agreement, the Libdems *promised* to look into alternatives to Trident, but - and here's a shock - they broke their solemn promise and they let the £350 million on new nuclear missile submarines sail through, with nary an earmark for any other sort of plausible alternative.

Still, this is a big deal - we are not only putting a truly vast sum of money at stake - the defence contractors estimate £25 billion, so we can assume at least three times that, 10 years late - we are also binding ourselves into a strategic commitment to maintaining not just a nuclear arsenal, but to a uniquely cold-war era one, based around submarine launched ballistic missiles.

The question someone in parliament - be they a pinko, dope-smoking commie-coddling lefty pacifist, or an austerity loving, state-hating, swivel eyed right winger - should be asking is "Would Britain in the mid-21st century become a significantly less safe place if we possessed different, cheaper nuclear weapons?"

Even if you leave aside the moral arguments around nuclear weapons - and I'm sure BAE Systems Submarine Solutions, unlikely to rebrand any time as Ocean Going Holocaust Delivery Mechanism Manufacturers Inc any time soon - would like us to, there are compelling practical arguments for a different kind of weapons system. A real public argument around what form our should take deterrent, or indeed, whether we should have one at all, and about defence generally, is badly needed.

If you look around, and ask the forbidden question, "what are the plausible threats to Britain?", the Trident system becomes increasingly suspect.

Does it stop Terrorism? Do nuclear weapons deter that? Where are we going to fire a Trident in retaliation for a terrorist attack? Mecca? Belfast? Bradford?

Is it a deterrent to rising powers like China or Russia? If Britain were to stand alone in a showdown with nukes on the table, it would be doomed. The UK's security against big power aggression must depend on our alliance with the USA. It's hard to swallow but sadly true - and in any case, the trident system is totally reliant on US technology, expertise and support, so any idea it is an "independent deterrent" is sadly flawed.

Of course, there is a real threat that could be deterred from rogue states like Iran or France. But we must ask ourselves the question, is a ballistic missile system the best answer for that? There is an important distinction between retaining a some nuclear weapons and none at all.

Are cheaper nuclear cruise missiles fired from cheaper, multirole attack submarines any less deterring? Are they less deterring if the missile is fired from a ship? From a plane? From a really big cannon?

I'd conclude that they are slightly less deterring, but only slightly - there is a slim chance of shooting down a cruise missile, or destroying an aircraft before it launches one. But it ignores the reality that there could be tens or hundreds coming through - it's not a chance I'd bet on, when losing the bet is a whole city and hundreds of thousands of people burned to ashes. It's a gamble someone would only take if they probably wouldn't be deterred by our ballistic missiles anyway.

The arguments deployed for keeping Trident, rather than some other system, are often weak, even laughable. Notably, some worry about trifles like the international legality of cruise missiles - as though a bomb that incinerates hundreds of thousands is fine so long as it drops vertically rather than horizontally. Among those who want to keep Trident, probably the most cited, but least convincing, is what is known in the as the "big willy" argument.

This argues that Britain's influence - our permanent UN security council seat, our trade links, our ability to have David Cameron cheering for Chelsea in the White House situation room - would be in jeopardy if we began dismantling some of our nuclear weapons. This is tragic, 1950s, post-imperial thinking. National security is vital - but having a massive willy to wave in the faces of other leaders is not.

That's not to say there aren't some convincing reasons to have a like-for-like replacement - I just wish we would have those discussions openly, unfettered by weak-kneed short-term political calculations. What we really need is real debate on the topic - personally, I'm sure we can be just as safe if Mr. Cameron decides he can cope with a little circumcision.

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