One of the most intriguing questions about morality, it seems to me, is what happens when it changes. What happens, for example, when the subordination of women to men, or their exclusion from higher education or the professions, ceases to seem innocuous or natural, and starts to be regarded as a grotesque abuse? Or when corporal punishment goes out of style, and homosexuality comes to be tolerated or even respected, or when cruelty to animals arouses indignation rather than indifference, and recklessness with natural resources becomes a badge not of magnificence but of monstrous irresponsibility?
There is of course room for disagreement about such alterations of moral opinion. But no one could maintain that they are devoid of discussible intellectual content. No one would claim that – like, say, changing fashions in moustaches or skirt-lengths – they simply reflect the unaccountable gyrations of taste. Indeed it seems probable that moral change, over the long term, involves something like an expansion of horizons, a process of learning, or even – to use a dated word – something you might call progress.
It seems timely, therefore, to turn back to Immanuel Kant’s celebrated treatment of the question “whether the human race is continually improving”. Writing in the 1790s, Kant argued that the “moral tendency” of humanity was, like human knowledge as a whole, destined to carry on getting better till there was no room for further improvement: humanity was imbued, he thought, with a transcendental impulse to refine and clarify its moral opinions as time goes by, or to grow in moral intelligence.
Kant’s faith in moral progress was popular in the nineteenth century (think of Auguste Comte’s Positivism and various branches of Hegelianism), but it is not likely to be promoted with much conviction any more. If you were to show any signs of moral optimism today you would be mocked as the dupe of political boosterism or moral grade-inflation, and friends would try to re-educate you with a catalogue of ferocious wars, futile revolutions and murderous regimes, topped off with some sad sagacity about the destructiveness and deceitfulness of human nature. The old proverb about pride applies to moral optimism as well, or so you would be told: hope comes before a fall.