Whether nuclear deterrence can be justified in terms of peace ethics is a question that has been widely slipping out of public focus after the end of Cold War. Ever since the rising tensions between North Korea and the U.S. and the threat to use nuclear weapons it has been intensively debated again. The end of the bipolar world order and the new global political constellations with their higher degree of complexity induce numerous actors – among them many representatives of the churches – to negate this question today. Already in the 1950s, the Protestant Church threatened to split over it. With the “Heidelberg Theses” of 1959 and their concept of “complementarity” it succeeded in hedging the contentious issues associated with the two mutually exclusive possibilities – keeping the peace through military means (including nuclear weapons) or by a complete renunciation of force. The underlying idea of mutual conditionality was lost in the further course of the debate, and has now given way to an either/or choice.
Yet neither the demand to abandon nuclear weapons nor their possession for deterrence purposes is without contradictions. Both ways – an unilateral renunciation while nuclear weapons stay in the hands of autocrats as well as the threat to use weapons that may never be used – harbour dilemmas. Recourse to the complementarity of the Heidelberg theses, including the eighth thesis which states that nuclear deterrence is a “still possible” ethical option, does not negate the goal of a nuclear-weapon-free world, but emphasizes the process nature of peace. The word “still” is linked with far-reaching disarmament policy measures. We will not be able to do without the basic idea of common security. This requires confidence-building measures – this approach is not new, but has been seriously neglected in recent decades, including in debates within the Church.