Nuclear Deterrence and Logic In principle, if the consequences of the failure of a system would be infinitely destructive to a civilisation, it is reasonable for that civilisation to use that system if and only if the probability of its failure are zero. Does the possession of nuclear weapons by a number of states in the international community constitute a system, that is, a group of interrelated parts forming a whole? It is certain that they are interrelated; the possession of these weapons by one state is indeed the driver for a second state to obtain its own weapons, forming a chain reaction of nuclear weapons proliferation which the NPT seeks, with surprising success, to restrain. They also form a system in the sense of classical Mutual Assured Destruction (MAD) deterrence, whereby opposed states are restrained from using their weapons in warfare because of the threat of retaliation by its opponent. So nuclear weapons do form a group of interrelated parts. Do they form a whole? In classical deterrence, the answer given by supporters of deterrence theory was a categorical affirmative. For them, the balance of nuclear forces between West and East created a state of peace for fifty years. A more neutral point of view would agree that the existence of nuclear weapons does indeed raise the threshold for declaring war. So all parties can agree that the outcome of collective nuclear weapons possession is an inhibition of declaration of war, a relative state of world peace, which is the single product of the many parts, and therefore nuclear weapons possession on the part of many nations is a system. Next, can the system fail? Nuclear deterrence is a complex arrangement of electronic sensors embedded in a command and control network composed of humans working to hard protocols that are interwoven with pattern judgements and valuations which are affected by the emotional state of the individuals and groups that make the judgements. The groups themselves, particularly the supreme decision making groups, are isolated from the common body of humanity, and are known to be susceptible to a condition known as group think – defined as A mode of thinking that people engage in when they are deeply involved in a cohesive in-group, when the members' strivings for unanimity override their motivation to realistically appraise alternative courses of action. Moreover, the interplay of decision makers is now far more complex than in the days of the cold war, with players coming on to the field who might not view the destruction of the prevailing world civilisation as a thing to be avoided at all costs, and other players already on the scene who believe that nuclear weapons could be used tactically without risking a strategic exchange. In short, it is entirely reasonable to judge that the probability of failure of the nuclear deterrence system is greater than zero. Would the breakdown of the nuclear deterrence be infinitely destructive? This is point that must be settled by a value judgement. First, would it be possible to get away with a limited exchange, or would one nuclear detonation inevitably escalate into an all out global nuclear war? It is impossible to give a definitive answer to that question, but the safest assumption to make is that if one weapon is detonated, they will all be fired. The reason for this lies in the doctrine of first strike, which aims to destroy the opponent’s weapons before they can be fired. Once it is known that an opponent has detonated a nuclear weapon, the pressure will be on for supreme commanders to fire all their nuclear weapons before they lose them to a first strike. In view of this, although we cannot say that any exchange would inevitably lead to a first strike, it would be the height of folly for anyone to assume that they could use weapons in a limited tactical strike and believe that matters would then be allowed to rest by the opposition. Unfortunately this is the prevailing nuclear doctrine of the United States of America. They consider that nuclear weapons could be used tactically, as an extension of a conventional military campaign. In doing so, they may trigger an all-out nuclear war. Would an all out strategic nuclear exchange be infinitely destructive? There are estimated to be at least 27,000 nuclear weapons in the world held by at least eight countries, 96 percent of them in the possession of the United States and Russia. The effects of all-out nuclear war were well studied in the 1980s. Physically, the most interesting possible effect is the so-called Nuclear Winter, where atmospheric soot cuts off sunlight for a period of weeks or months. When the sunlight returns, the effects of city and forest fires will have been to increase the atmospheric CO2 load, thus exacerbating global warming. Species loss will increase, secondary to habitat loss. Of these, the loss of bees will be most important, since cessation of their pollination services will lead to failure of such crops as survivors may try to plant. Ironically, rats and cockroaches are resistant to radiation, and so will flourish, given the plentiful quantities of human and animal carrion available. To say the least, economic growth after a nuclear war would be unlikely. In fact a global economic recession or even a depression is almost inevitable, and to be replaced by a survival economy based around obtaining water, food, warmth and shelter for the group. Life will be short, and cancers plentiful, but health services would be rudimentary, and analgesics in short supply. Gangsterism will flourish, and self interest is likely to become the norm. In summary, it is entirely reasonable to expect that an all out nuclear exchange would lead to the end of western civilisation. It would therefore be infinitely destructive. In terms of the model set out at the beginning, the consequences of the failure of a nuclear deterrence system would indeed be infinitely destructive to our civilisation, the probability of its failure is greater than zero, and therefore it is illogical for our civilisation to use that system. Since the syllogism contains a value judgement, and there will inevitably be others who take a different view. However, they are compelled to argue either that the deterrence system is perfectly safe, which is manifestly not the case, or that a tactical weapon would not lead to an all-out nuclear war, which is clearly not provable, or that an all-out nuclear war would not destroy civilisation, which is clearly unreasonable. In the circumstances, however, because of the uncertainties involved, it is safer to take a precautionary view. The great majority of humanity view the possibility of all out nuclear war with a great deal of distaste. They should be helped to understand that the nuclear deterrence system is not infallible, and that these weapons are quite capable of being used in anger. This should then motivate them to exercise their democratic right and duty to remove from political office anyone who believes that it is reasonable for any state to possess nuclear weapons. Dr Richard Lawson