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The Risk that Humans Will Soon Be Extinct

  • John Leslie (a1)

If it survives for a little longer, the human race will probably start to spread across its galaxy. Germ warfare, though, or environmental collapse or many another factor might shortly drive humans to extinction. Are they likely to avoid it? Well, suppose they spread across the galaxy. Of all humans who would ever have been born, maybe only one in a hundred thousand would have lived as early as you. If, in contrast, humans soon became extinct then because of the population explosion you would have been ‘fairly ordinary’. Roughly ten per cent of all humans would have been your contemporaries. Now (as the cosmologist Brandon Carter saw to his dismay) a scientific principle tells us not to treat observations as highly extraordinary when they could easily be fairly ordinary. How to apply the principle is controversial, yet it seems we can safely conclude that humanity's chances of galactic colonization cannot be high. Still, we should work to make them as high as possible, resisting those philosophers who argue that human extinction would be no tragedy.

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1 Leslie, , The End of the World (London and New York: Routledge, 1996). For interesting recent papers on the risk of human extinction, see Global Catastrophic Risks, (eds.) N. Bostrom and M. M. Circovik (Oxford: Oxford University Press, 2008). See also Joy, Bill, ‘Why the Future Doesn't Need Us’, Wired (April, 2000), 238262: ‘Our most powerful 21st-century technologies – robotics, genetic engineering, and nanotech – are threatening to make humans an endangered species’ is the summary at the head of this influential article. Global warming is discussed expertly by Hansen, James, director of the NASA Goddard Institute for Space Studies, in his Storms of My Grandchildren: The Truth About the Coming Climate Catastrophe and Our Last Chance to Save Humanity (New York: Bloomsbury, 2009).

2 Rees, M., Our Final Century (London: Heinemann, 2003).

3 Moravec, H., Mind Children (Cambridge, Mass.: Harvard University Press, 1998).

4 I discuss these things in The End of the World and in chapter two of Infinite Minds (Oxford University Press: Clarendon Press, 2001).

5 Weinberg, S., Dreams of a Final Theory (London: Hutchinson, 1993). See 187–188 in particular.

6 Rees, and Hut, , ‘How stable is our vacuum?’, Nature 302 (April, 1983), 508509.

7 Rees, , Before the Beginning (Reading, Mass.: Addison-Wesley, 1997). The quotation is from page 207.

8 Rees, Our Final Century (London: Heinemann, 2003), 122.

9 Sher, M., ‘Electroweak Higgs potentials and vacuum stability’, Physics Reports 5 and 6 (1989), 273418; see especially 335–336.

10 Brown, N., New Strategy Through Space (Leicester: Leicester University Press, 1990); see especially page 85.

11 In The End of the World, which also includes much detailed discussion of many doomsday scenarios (it even mentions – for storm clouds could be seen approaching even in 1996 – a tiny risk associated with world-wide economic collapse, ‘the huge U.S. governmental, commercial and household debt’ and ‘stock-market trading in derivative securities’ combining to ‘vaporize financial markets’); in several articles, for instance ‘Time and the anthropic principle’, Mind 101 (1992) 521–540; in 12–14 of Immortality Defended (Oxford: Blackwell, 2007); and during a tour as the British Academy-Royal Society of Canada Exchange Lecturer (I thank the British Academy for financing it).

12 Gott, R., ‘Implications of the Copernican principle for our future prospects’, Nature 363 (May, 1993), 315319.

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  • ISSN: 0031-8191
  • EISSN: 1469-817X
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