IN this week's TV debate Patrick Harvie, co-convenor of the Scottish Green Party, claimed that the only purpose of nuclear weapons is the mass slaughter of the innocent, and that Scotland's expulsion of Trident would put disarmament back on the international agenda.

He is wrong on both counts.

First, the primary purpose of possessing nuclear weapons is deterrence. Just imagine how much more overt Valdimir Putin's aggression in Ukraine would now be if he were unconstrained by the possibility of nuclear conflict with the west.

What is more, Trident's missiles are not targeted on population centres (or anywhere else), and for all we know, the Prime Minister's secret instructions in the event of a nuclear attack on the UK are not to retaliate.

Secondly, the removal of nuclear weapons from Faslane, even if it were to precipitate the UK's unilateral disarmament, would have no effect whatsoever on the United States or France, not to speak of Russia, China, Pakistan, or North Korea.

So Scotland's repudiation of Trident would be an empty moral gesture, doing nothing for international disarmament, and leaving the Scots in the hypocritical position of free-riding on American nuclear defence.

Nuclear weapons are not the cause of international mistrust, but the effect. Unilateral disarmament would not make the world a safer place.

Nigel Biggar,

Professor of Christian Ethics.

Oxford University,

Wellington Square, Oxford.

BRIAN M Quail (Letters, September 4) insinuates that we "threaten the world with global nuclear suicide" and that we will go on believing that we are wee, poor and stupid unless we dump the United Kingdom's nuclear weapons. No-one actually believes that Scotland's citizens are that, and anyway, Scotland's great history totally disabuses anyone who might be prone to.

There is a case for the UK to put more effort into achieving global nuclear disarmament, but unilateral action makes no difference to what goes on away from Scotland. Possession of nuclear weapons and their delivery systems seem to be a prerequisite for the UK's permanent membership of the UN Security Council, giving reach and influence, so however regrettable having them may be, expediency rules.

I never thought I would say that, having at one time been active in CND demos, but given the current unrest all over, having a UK presence at the top tables is essential.

Let's not jeopardise that at this time.

Joe Darby,

Glenburn,

St Martins Mill,

Cullicudden,

Dingwall.