Thinking logically about Trident

Mary Dejevski writes in the Independent today (The nationalists, the whistleblower and a chance to think about Trident, p 28, 19 May) hopes that the scrutiny of Trident will go beyond the specific complaints made by the courageous whistleblower, William McNeillie. If only we could hope for such scrutiny.

Here is the ultimate question about Trident:

Is there a greater than zero probability of its being fired?

If the answer to that question is an unqualified no, then we can safely continue with it, although there are questions about its cost and the potential for accidents, but these downsides can be balanced by Trident's effect in raising the threshold at which nuclear weapons states will declare war on us.

If the answer is yes, there is a chance that it could be fired, then we must abandon the whole idea of nuclear deterrence, and work intensively to ensure a global ban on all such WMD.

There is a cast iron reason for this: if the consequence of the breakdown of a system is infinitely destructive, it is reasonable to use that system if and only if the probability of its breakdown is zero.

Any examination of the history and structure of nuclear deterrence will quickly conclude that there is a greater than zero chance of deterrence failing.

In that case, Trident will be the trigger for, or part of, a global nuclear holocaust, with all 17,000 being fired or destroyed in their silos. That will destroy human civilisation - an infinitely negative consequence.

That being the case, we must put an end to the Trident programme. If between them the SNP and William McNeilly have started a radical, logical reappraisal of nuclear deterrence, they will have done the whole world an immense favour.