“A Letter on Human Nature” (1986), letter to Beata Polanowska-Sygulska, New York Review of Books, 23 September, 26, 2004.
“First, then, let me talk about the difficult question of “human nature.” Do I believe in a fixed and unalterable human nature?—you rightly quote me as saying that I do not, and then again rightly quote me as referring to it as the basis of human communication. What, then, do I believe? I wish I could answer this question with extreme precision, but it does not seem to me to lend itself to that. What, I think, I believe is that there are thinkers, principally believers in Natural Law, who propose that all men are created, whether by God or Nature, endowed with innate knowledge of certain truths—some “factual,” some normative—the lists differ from Aristotle, the Stoics, Isidor of Seville, Gratian, Grotius, etc., but for the most part they include the existence of God, the knowledge of good and evil, right and wrong, the obligation to tell the truth, return debts, keep promises (pacta sunt servanda), some or all of the biblical Ten Commandments, and so on.
I do not know who first questioned this—I dare say Epicurus or Lucretius—but in modern times the main attack upon this was delivered by thinkers like Vico and Herder and Marx (and, indeed, Hegel and his followers), and, of course, the empiricists, not Locke but Hume and his followers: according to whom, whatever the status of these Natural Laws, primitive men did not possess knowledge or even awareness of them, and they came into consciousness, or, indeed, formed objects of belief or certainty, in the course of evolution, or under the influence of changes in material circumstances and the growth of culture (whatever factors enter into that); for this entails that human beings go through a process of moral or metaphysical growth and development; and this is as valid as that empirical knowledge is an onward-going process, whether one believes that it tends to progressive development towards some kind of perfection (which it may never reach) or not—that it is cumulative but possesses no identifiable structure or teleological tendency.”