The arguments we consider in this chapter are about nuclear deterrence. This is a subject in which reasoning plays an enormously important part. Deciding which is the best policy is not simply a matter of discovering the facts about the weapons systems available to the two sides because it is hard to tell what these facts imply about intentions under deterrence, nor is it simply a matter of resolving to defend oneself since the difference between defensive and aggressive acts is obscure under deterrence. The importance of the arguments cannot be disputed, so how should we resolve them?

This chapter attempts to contribute to the debate not directly, but by explaining a method of analysing arguments using two specimen texts from the very extensive literature on the subject. The texts we have chosen are quite typical: there are certainly many other pieces expressing similar arguments and no doubt many of these would have served our purpose equally well; however, our focus of interest is not on these particular texts (typical or not) but in the method of assessing them. We succeed in our objective if the reader grasps the method of analysis explained by reference to these examples and is then able to apply it to other pieces of reasoning.