Nuclear holocaust

==Moral importance of human extinction risk==
{{Main|Human extinction#Ethics}}

In his book ''[[Reasons and Persons]]'', philosopher [[Derek Parfit]] posed the following question:<ref>{{cite book |title=Reasons and Persons |first=Derek |last=Parfit |author-link=Derek Parfit |publisher=[[Oxford University Press]] |year=1986 |chapter=154. How both human history, and the history of ethics, maybe just beginning|title-link=Reasons and Persons }}</ref>
<blockquote>Compare three outcomes:
#Peace.
#A nuclear war that kills 99% of the world's existing population.
#A nuclear war that kills 100%.
(2) would be worse than (1), and (3) would be worse than (2). Which is the greater of these two differences?</blockquote>
He continues that "Most people believe that the greater difference is between (1) and (2). I believe that the difference between (2) and (3) is ''very much'' greater." Thus, he argues, even if it would be bad if massive numbers of humans died, human extinction would itself be much worse because it prevents the existence of all future generations. And given the magnitude of the calamity were the human race to become extinct, [[Nick Bostrom]] argues that there is an overwhelming moral imperative to reduce even small risks of [[human extinction]].<ref>{{cite journal |doi=10.1111/1758-5899.12002 |first=Nick |last=Bostrom |author-link=Nick Bostrom |title=Existential Risk Prevention as Global Priority |journal=[[Global Policy]] |volume=4 |issue=1 |year=2013 |pages=15–31 |url=http://www.existential-risk.org/concept.html}}</ref>