Charles T. Rubin in The New Atlantis:
The ambiguity in the meaning of moral progress is at the heart of a 1923 debate between biochemist J. B. S. Haldane and logician Bertrand Russell, two of the greatest and most argumentative public intellectuals of twentieth-century Britain. Haldane, who would go on to an extremely distinguished career as a biochemist and geneticist, spoke under the auspices of the Cambridge Heretics discussion club. Russell, already a famous philosopher, answered him as part of a speakers series sponsored by the Fabian Society under the general title, “Is Civilization Decaying?” The published version of Haldane’s remarks created no little controversy; even Albert Einstein had a copy in his library. There is also little question that Haldane’s work influenced two of the greatest British critics of scientific and technological progress: Julian Huxley and C. S. Lewis.
The titles of the essays, Haldane using Daedalus and Russell Icarus, support the common idea that Haldane writes as an advocate of progress and Russell as a skeptic. While this view is understandable, it is hardly exhaustive. Haldane freely highlights horrible possibilities for the future, and he is quite blunt about the socially problematic character of scientific research and scientists. Russell, on the other hand, can imagine circumstances (albeit unlikely ones) where the power of science could be ethically or socially constrained. The real argument is about the meaning of and prospects for moral progress, a debate as relevant today as it was then. Haldane believed that morality must (and will) adapt to novel material conditions of life by developing novel ideals. Russell feared for the future because he doubted the ability of human beings to generate sufficient “kindliness” to employ the great powers unleashed by modern science to socially good ends.