Probably very few people accept the ‘political’ arguments against British participation in the nuclear deterrent system; the arguments that British unilateral nuclear disarmament will encourage an Afro-Asian movement leading to multilateral disarmament, and that, whether or not the present Western deterrent is immoral, Britain is entitled to withdraw from it and expel its bases in order to cut down her risks in the event of war actually breaking out. But the traditional teaching of the Church on war and murder suggests to many Catholics that the deterrent system involves immoral risks and intentions, and must therefore be rejected on these grounds whatever the consequences may be. Now that this traditional teaching on war and murder is being clearly set out, fewer and fewer people will be able to hold that it is inapplicable to modern conditions. Yet, given this teaching, the current arguments from risks and intentions are still not strong enough to convince the majority who support nuclear deterrence. As the Revd. A. Kenny pointed out recently, even Mr Stein’s symposium has not quite succeeded in refuting the ‘theory of deterrence by bluff’: it is not selfevident that the risks involved in nuclear deterrence are too heavy to take; and because it is very difficult to show that Western governments themselves have an immoral intention to use the deterrent weapons immorally in certain circumstances, it would have been better if the symposiasts had pointed to the fact that, if the operators of the deterrent must be ready to act on governmental orders to launch the weapons against normal cities at a moment’s notice, then it is psychologically impossible for them, at least, not to have immoral intentions.