“Within a few centuries, it will be technically if not ideologically feasible to abolish suffering of any kind. If we wish to do so, then genetic engineering and nanotechnology can be used to banish unpleasant modes of consciousness from the living world. In their place, gradients of life-long, genetically pre-programmed well-being may animate our descendants instead. Millennia if not centuries hence, the world’s last aversive experience may even be a precisely dateable event: perhaps a minor pain in an obscure marine invertebrate.

Far-fetched? Right now, the abolitionist project sounds fanciful. The task of redesigning our legacy-wetware still seems daunting. Rewriting the vertebrate genome, and re-engineering the global ecosystem, certainly pose immense scientific challenges even to a technologically advanced civilisation.

The ideological obstacles to a happy world, however, are more formidable still. For we’ve learned how to rationalise the need for mental pain – even though its nastier varieties blight innumerable lives, and even though its very existence will soon become optional.”