"I believe that there is, from the ethical point of view, no symmetry between suffering and happiness, or between pain and pleasure. Both the greatest happiness principle of the Utilitarians and Kant's principle, "Promote other people's happiness...", seem to me (at least in their formulations) fundamentally wrong in this point, which is, however, not one for rational argument... In my opinion human suffering makes a direct moral appeal for help, while there is no similar call to increase the happiness of a man who is doing well anyway."
(The Open Society and Its Enemies, 1952)
The term "negative utilitariaism" (NU) was coined by Sir Karl Popper (Popper, Karl: 1952. The Open Society and its Enemies. Princeton N.J.: Princeton University Press. vol.I ch.5, note 6). The concept of negative utilitarianism was foreshadowed earlier e.g. in the work of Edmund Gurney (1847-88). It has obvious affinities with Buddhism. At first blush, NU appears to entail mass euthanasia, although this implication has been disputed.
Karl Popper was both a philosopher of science and a political philosopher. He is perhaps most famous for his falsification principle (The Logic of Scientific Discovery, 1934), a proposed methodological rule to demarcate science from non-science.
Popper's "negative utilitarian" principle is that we should act to minimise suffering rather than maximise pleasure. Classical utilitarian philosophers such as Henry Sidgwick had explicitly argued for the moral symmetry of happiness and suffering. Complications aside, they supposed that increases in happiness, and reductions in suffering, are essentially of equal value when of equal magnitude. Popper disagreed. He believed that the practical consequences of the supposed moral symmetry were dangerous too. "Philosophers should consider the fact that the greatest happiness principle can easily be made an excuse for a benevolent dictatorship. We should replace it by a more modest and more realistic principle: the principle that the fight against avoidable misery should be a recognized aim of public policy, while the increase of happiness should be left, in the main, to private initiative."
Popper believed that by acting to minimise suffering, we avoid the terrible risks of "utopianism", by which he had in mind the communist and fascist dictatorships of the twentieth century. "Those who promise us paradise on earth never produced anything but a hell." A staunch advocate of the "open society", Popper defended "piecemeal social engineering" rather than grandiose state planning.
Ironically, the full realisation of a negative utilitarian ethic depends inescapably on the "utopian" planning that Popper abhorred. Only a global bioengineering project of unparalleled ambition could bring about the eradication of suffering throughout the living world - not piecemeal social engineering. In seeking to liberate the world from the tyranny of pain, negative utilitarianism is no less "totalitarian" in its policy implications than communism or fascism, albeit vastly more compassionate.
It is an irony that Sir Karl would not have appreciated.