Abstract

Recent existential-risk thinkers have noted that the analysis of the fine-tuning argument for God’s existence, and the analysis of certain forms of existential risk, employ similar types of reasoning. This paper argues that insofar as the “many worlds objection” undermines the inference to God’s existence from universal fine-tuning, then a similar many worlds objection undermines the inference that the historic risk of global nuclear catastrophe has been low from the lack of such a catastrophe has occurred in our world. A version of the fine-tuning argument applied to nuclear risk, The Nuclear Fine-Tuning Argument, utilizes the set of nuclear close calls to show that 1) conventional explanations fail to adequately explain how we have survived thus far and 2) the existence of many worlds provides an adequate explanation. This is because, if there are many worlds, observers are disproportionately more likely to reflect upon a world that hasn’t had a global nuclear catastrophe than upon one that has had a global nuclear catastrophe. This selection bias results from the catastrophic nature of such an event. This argument extends generally to all global catastrophic risks that both A) have been historic threats and B) would result in a significantly lower global population.