Humanity's End

From Life and Mind: Philosophical Issues in Biology and Psychology

Humanity's End

Why We Should Reject Radical Enhancement

By Nicholas Agar

An argument that achieving millennial life spans or monumental intellects will destroy values that give meaning to human lives.

A Bradford Book





An argument that achieving millennial life spans or monumental intellects will destroy values that give meaning to human lives.

Proposals to make us smarter than the greatest geniuses or to add thousands of years to our life spans seem fit only for the spam folder or trash can. And yet this is what contemporary advocates of radical enhancement offer in all seriousness. They present a variety of technologies and therapies that will expand our capacities far beyond what is currently possible for human beings. In Humanity's End, Nicholas Agar argues against radical enhancement, describing its destructive consequences.

Agar examines the proposals of four prominent radical enhancers: Ray Kurzweil, who argues that technology will enable our escape from human biology; Aubrey de Grey, who calls for anti-aging therapies that will achieve “longevity escape velocity”; Nick Bostrom, who defends the morality and rationality of enhancement; and James Hughes, who envisions a harmonious democracy of the enhanced and the unenhanced. Agar argues that the outcomes of radical enhancement could be darker than the rosy futures described by these thinkers. The most dramatic means of enhancing our cognitive powers could in fact kill us; the radical extension of our life span could eliminate experiences of great value from our lives; and a situation in which some humans are radically enhanced and others are not could lead to tyranny of posthumans over humans.


Out of Print ISBN: 9780262014625 232 pp. | 6 in x 9 in


$25.00 X ISBN: 9780262525176 232 pp. | 6 in x 9 in


  • Penetrating and lucid…This is the definitive critique of what [Agar] calls 'radical enhancement.'

    Monash Bioethic Review

  • An evenhanded treatment of an area ripe for serious philosophical scrutiny. Agar's analysis is philosophically astute, empirically informed, and historically shrewd. It is a welcome corrective to the occasional extravagancies of the human sciences.

    Quarterly Review of Biology

  • Agar's book is a valuable survey of the most important interlocutors in the conversation about posthumanism...should be taken may well be persuaded by Agar's arguments.

    Journal of Interdisciplinary Studies


  • Arguments against radical enhancement have too often in the past been characterized by irrationalism and mysticism. Nicholas Agar presents the first cogent case for the rationality of opposing radical enhancement. Moving easily between science and philosophy, he argues for a species-relative conception of valuable experiences, according to which we have a strong reason to remain human. This central claim is bolstered by a host of other arguments, which will ensure that Humanity's End will become a central reference point for debates over the desirability of radical enhancement.

    Neil Levy

    Oxford Centre for Neuroethics

  • Nicholas Agar has written an excellent introduction to the moral challenges of our transition to a posthuman future, engagingly told by contrasting the work of four very different transhumanists. Humanity's End joins Agar's Liberal Eugenics on the must-read list for those interested in the future of the human race.

    James J. Hughes

    Executive Director, Institute for Ethics and Emerging Technologies


  • CHOICE Outstanding Academic Title, 2011