The Morality of the Nuclear Deterrent – how to decide for yourself

Background and Notes on the Flowchart


Along with climate change, nuclear weapons probably constitute the main danger to the world in this century. The concept of deterrence is behind nearly all of the possible modes of deployment of nuclear weapons and is a key part of the moral justification that is generally offered for retaining possession of them. Deterrence, in this context, is the property or effect of a weapon in preventing an aggressive act by the possibility of retaliation using the weapon. Deterrence may be enhanced by the implicit or declared intention to retaliate using the weapon. The intention may be real or unreal. The aggressive act to be prevented could include an attack by nuclear or by conventional forces. The flowchart is intended to examine the morality of using the deterrence property of nuclear weapons in any of these ways. This defines the scope of the flowchart.

To initiate, renew or maintain a nuclear deterrent, a state has to make significant decisions. Is there, in every case, sufficient consideration of the ethical dimension of the decision? Is it consistent with the standards which underpin the social fabric of national life? Responsible citizens will wish to give this some consideration. The flowchart is intended to help this process.


- why the nuclear questions must be answered as questions of personal morality:

Although every person in the world is threatened by nuclear weapons, responsibility must lie with individuals who can have some influence on the situation, especially if the weapons are deployed on their behalf. These people have a duty to carefully examine the situation and then to take the appropriate action. Therefore the following is addressed in particular to citizens of the existing nuclear weapons states (more so if they have well-functioning democracies) and of any states that may be contemplating development of nuclear weapons. Furthermore, people around the world, for whom it may be unacceptable that a few advanced countries can endanger the Earth for the sake of their own security, also need to make a rational and comprehensive analysis of the situation if they are to propose an effective and safe approach to disarmament.

People in the nuclear weapons states must identify with those actually wielding the weapons – politicians and military – because, in theory at least, it is being done for them and with their support. The flowchart therefore refers to ‘you’ and ‘we’ as being both the nation and the individual conscience. Remember it is up to you, personally. Before you decide that the weapons should be set aside you must face up to all that could follow, should your decision be implemented. On the other hand, if you accept the weapons for your defence, then morally, you hold them in your own hands.


To make the right choices there are many questions to be answered. The flow chart is an attempt to assemble all the strictly relevant questions, to get them in the best order and to show the relationships between them. All the questions are configured to have only two answers – basically Yes or No. This approach is intended to focus the reader onto a clear decision at each stage and to give a simple complete analysis by which our different decision paths can be readily compared.

The order for the questions is itself debatable, but the following principles are applied:

  1. Fundamental or more widely applicable questions should be answered first, e.g.: Can it be right to kill people? must come before: Can we justify the expenditure?
  2. Whatever course you take you should answer all the questions relevant to the consequence of your choices. Thus for example a pacifist should face up to all the risks of unilateral disarmament. There is a proposed order and allocation for a whole range of important consequential issues – proliferation, escalation of capability, imposition of risks on third parties, environmental destruction, misuse of resources, effect on conventional warfare and so on.
  3. In some cases the order is not very critical, and in this case the seemingly more urgent issues are dealt with first, e.g. nowadays it seems more relevant to consider proliferation before escalation of capability.
  4. You can of course change the order according to your own judgement, provided you are confident that the overall analysis is still rational and complete.

It is hard to be unbiased in formulating the questions. On which side should be the onus of proof? However the emphasis of the questions can be adjusted by the readers, according to their own opinion, without, in many cases, necessitating a re-arrangement of the flow of questions in the chart. On the other hand, where a significant change is made it is important to check and amend the logic downstream of the change, to ensure a consistent logical structure.

There are three routes out of the chart, corresponding to three basic points of view:

  1. Those who conclude that the deterrent is immoral and therefore renounce it. (42, 43)
  2. Those who regard it as too dangerous or ineffective or indirectly immoral and would therefore wish to abolish it (possibly by unilateral disarmament). (44)
  3. Those who see the nuclear deterrent as morally acceptable and the best route to security. (46)

The principle of individual responsibility is maintained, so that, particularly if you take routes 1 or 3, there are many hard questions to be answered. Significant further action is proposed if you take routes 1 or 2. Route 3, which for the nuclear states corresponds roughly to the status quo, requires less action but carries no less responsibility.


(The notes are referenced to the chart by the numbers allocated to the questions and comments.)

1, 2 No notes.

3 etc. In this chart “state” means ‘country’ or ‘nation-state’ in the modern sense of the words.

4 No notes.

5 The implication here is that civilian casualties are not intended but are a likely outcome.

6 “a deliberate policy” In this case the civilian casualties are seen as an inevitable or intended, consequence of the action, e.g. as in carpet bombing of cities in World War 2.

7 Deliberate targeting of a civilian population was certainly not regarded as acceptable at the beginning of WW2. However, by the end of the war the western allies routinely took this action. The policy was opposed by many during the war, but in 1945 it effectively provided a precedent or way of thinking in which the escalation to the use of atomic weapons on Japan was a relatively small step. The policy of conventional mass bombing that was adopted during the war has since been generally condemned but this moral judgement on WW2 has not generally been extended to cover nuclear weapons deployed as a deterrent, a concept partly derived from the WW2 policy.

8 No notes.

9, 10 and 11 For the first 40 years of nuclear deterrence, weapons were deliberately aimed at cities, to ensure the most terrible consequences of use, which of course included the destruction of countless innocent lives. Through improved accuracy, the weapons can now be aimed more specifically at military installations, invading forces or vital infrastructure, with the intention, at any rate, of reducing innocent casualties. Deterrence might be preserved (it is argued that assured defeat could be a more effective deterrent than assured destruction) but there are hard practical questions with huge moral implications. Having in mind the awesome destructive power available, the devastation and the long-term radiation which goes on killing indiscriminately, it is an inevitable consequence that innocent lives would be taken. If you think that destruction of some innocent lives as the inevitable result of an action, could be acceptable, then you could say Yes to Q10. But then you have to decide how much killing can be justified, and estimate how much will happen. You have to make a judgement of this and allow for a high level of uncertainty in the outcome. Unfortunately your limited strike policy means that at that stage you could well be fighting a nuclear war. Would the moral constraints of your policy then have much influence on the actions of your armed forces? Your potential enemy could be expected to anticipate this scenario and so initial deterrence could be enhanced by these “unintended” possible consequences. But are you then relying on a de‑facto threat of indiscriminate mass destruction? These questions are not for the future - you have to decide now.

12 No notes.

13 Moral acceptability of an effective threat?

Firstly, could it be totally effective? Some people say that the effectiveness has been demonstrated - so far. Others will say that this is unacceptable evidence because the consequences of failure make it an unacceptable test – if it fails, who will be there to say so?

Secondly, we have to assess the possibility of accidental use of the weapons.

Thirdly, we have to examine the possible thought processes of an aggressor:

14 Any potential aggressor could be expected to think ahead to analyse your probable reaction in the situation of failed deterrence. He would almost certainly conclude that nuclear retaliation under these circumstances would be clearly contrary to any rational conscience.

15 No notes.

16 This is effectively a repetition of 13 in the light of the more detailed moral and practical implications (Comment 14).

17 No notes.

18, 19, 20 In these circumstances the morality of the nation’s position, and therefore of the individuals who support it, becomes a government secret. If this is to be taken seriously then acceptance of these conditions must lead to Question 24 etc.

21 A legitimate creation of uncertainty? But is it an implied threat rather than merely a perceived threat? If so, how is this different from 15? How much uncertainty do you want to generate if you are to be confident in your deterrent? How will this level of uncertainty affect motivation for proliferation, escalation of capability and preventive strike criteria? Those who rely on this principle to retain WMD with a good conscience must go on to deal with Question 24 etc.

22 and 23 If extremist and terrorist groups gain access to mass destruction weapons they will have immense powers to subvert legitimate organisations and governments. Some people have seen this as a reason for retention of nuclear weapons, so two questions are posed here for the ‘disarmers’. For these particular circumstances, they should consider whether nuclear deterrence could be effective, and if so, would it be morally acceptable. If you decide that for terrorism, nuclear deterrence could be both effective and acceptable, your more general moral conclusions from the forgoing questions should still be applicable, so your answer takes you to Comment 44. The alternative would be to go to Question 24. The non-national groups issue could also be examined as part of the proliferation problem, in which case it would be another test for those opting to retain the weapons, e.g. before Question 30.

24 Having accepted the deterrent in principle you now face further questions relating to whether it is acceptable for your country to possess a deterrent. You must ask: are we sufficiently responsible to possess weapons of mass destruction? You must come to some conclusion about the stability and effectiveness of your democracy, the collective morality of those who contribute to it and the stability of directly responsible individuals.

25 No notes.

26 If we decide that we need a deterrent for our security, then we should not be surprised when others come to the same conclusion. In fact they are far more likely to decide this when several other nations maintain a mass destruction capability. The outcome could be continued escalation and proliferation. Where would that end? The following questions on the practical outcome of proliferation are not strictly moral issues but there is arguably an additional moral question to test your response to the outcome of Question 31. Most people will not need this.

27, 28, 29 No notes.

30 This refers to escalation of capability rather than escalation of a conflict. There are two main aspects to consider: - (a) the historical record and (b) the theoretical approach.

(a) In the first 40 years of “deterrence” there was more than a million-fold escalation of total destructive capability relative to the explosions which destroyed Hiroshima and Nagasaki, during which time all parties involved were avowedly seeking multilateral disarmament. The end of the Cold War brought some respite but awesome destructive capability is still retained.

(b) The apparent insanity of multiple overkill is a result of weapons being targeted against weapons, i.e. their being deployed as a counter to the risk to deterrence, posed by enemy weapons. And is it logical to seek security through a balance of insecurity? The means being opposite to the ends, are they not bound to grow further apart?

31, 32, 33 No notes.

34 An immoral diversion of resources? For some people this is the number 1 question. These people generally reject the deterrent on the basis of its hideous cost in the face of so much real need in the world. They may wish to reconfigure the chart accordingly, but the fundamental questions about deterrence are still to be answered and in any case they should still consider the questions following Note 35.

However, some people answer Yes to 34 on the basis that the nuclear deterrent is a cost‑effective means of defence and that there is no direct relationship between expenditure on aid to the poor and expenditure on defence. The others maintain that the two approaches are directly opposed: morally as a choice between comforting and confronting, i.e. loving and trusting as opposed to hating and fearing; and economically as being alternative routes to security.

35 and 36, 38, 40 Those who take on a pacifist or abolitionist position must still be challenged with the possible consequences of their actions in the world as we find it now:

36 Various risks are proposed.: Immediate disarmament might have a destabilising effect. Progressive reduction to zero capability might give increased incentive for proliferation and for counter-population targeting. And having given up NW you might expect a lack of influence in a dangerous world.

37 No notes.

38 You have to face the long term, or indefinite, prospect that, in effect, the most powerful of the instruments of evil could be wielded only by the people intent on evil. However, most people will see that there are control methods and that these must not incorporate the evil - if they do they have failed.

39 In 38 you have made a practical judgement of the possibility of subjugation. Now you must decide whether you can accept this possibility. If not, then you may answer Yes to 39. Morally this is a compromise rather than a simple judgement. (e.g. Christians should not be surprised to find that the advent of mass destruction weapons is forcing them to reconsider what was for them a compromise in the first place, namely, the acceptance of the Just War position in the face of the teaching and example of Christ Himself.)

Also, it is arguable that to answer Yes here, is to accept in principle the right or even necessity for all states to possess nuclear weapons, if these are the only effective means of defence. (Q 26)

40, 41, 42, 43, 44, 45, 46 No notes.

47 - a new question to cover deterrence of non-nuclear forces. From the earliest days of the Cold War, western nations deployed nuclear weapons as a deterrent against attack by conventional forces and they have never renounced this policy by a ‘no first use’ undertaking. Q47 is not about defeat of conventional forces, it is about deterring invasion by a threat of overwhelming destruction (hence ref. to WMD). However, nuclear weapons deployed directly against conventional forces also come within the scope of the flowchart in that there is an element of deterrence in their effect. In this case Q9, 10 and 11 are applicable.


For practical simplicity the flowchart indicates only three exit points. Those who come out by Route 2 (Comment 44) will see that it includes a variety of moral and practical positions which are defined, in effect, by how they were arrived at. Therefore, in order to decide your further action it is advisable to trace back your decision path to see what is and what is not acceptable to you.

All the nuclear armed nations have used their domestic nuclear energy capacity in support of achieving the capability for mass destruction weapons. Partly for this reason, many who hope to abolish nuclear weapons would do the same for nuclear energy. But it should be noted that the capability for nuclear energy generation is not a moral issue within the scope of this chart. However, it is surely significant that the generally successful policing for non-proliferation of weapons, developed in the context of nuclear energy, would be applicable in the policing of abolition and prohibition of nuclear weapons.


To be most widely applicable this chart is configured as a secular document. However, all faith communities are invited to develop versions for their own use. Other people may wish to amend the chart as part of their individual response. Please enquire (contact details below).

The flowchart is available for free download at . Hard copies are available. Contact Martin Birdseye +44 (0)77 6274 6895 martin at

Remember, if the nuclear deterrent is deployed on your behalf, then it is your responsibility.