Suppose you knew that after your natural death the human race would die out – perhaps, for some reason, humans had become infertile. How would that alter how you live your life? How would it change your attitude to the ideas and projects to which you are currently committed? This thought experiment is posed by American philosopher Samuel Scheffler. He believes that in this scenario, most of what currently gives our life significance would come to feel meaningless. This leads him to conclude that we care deeply about the survival of our species. We need the human race to survive for our lives to seem valuable. Presenter David Edmonds Producer Ben Cooper