What is it that determines humans in their opinions and emotions? Hume distinguishes between two kinds of causes: (1) physical causes such as the air and climate; (2) moral causes such as custom and education. In his essay On National Characters (1748), Hume clearly opts for the latter:
“If we run over the globe, or revolve the annals of history, we shall discover every where signs of a sympathy or contagion of manners, none of the influence of air or climate.”
What is so special about Hume’s answer? – In my book on Socialising Minds, the first draft of which I am currently revising, I argue that Hume’s rejection of physical causes as determinants of human mentalities is owing to Hume’s intersubjective understanding of the mind. Much of what we think and feel depends on other surrounding minds and not simply on a shared physical environment. However, in trying to come to grips with Hume’s account I noticed that his reply should be read as part of an intricate debate about the causes of the mentality of groups. In what follows, I’d like to raise a few questions about the intriguing context of the debate that I think Hume is participating in.
How, then, should we contextualise what Hume is saying? – As might seem obvious, Hume distinguishes two positions in line either with physical or moral causes. Readers of his Treatise will recognise his opting for sympathy and thus moral causes as an endorsement of his theory of sympathy. But what is he rejecting? As I already noted earlier, he rejects the so-called climate theory. The climate theory explains the character of people by reference to the climate and physical conditions of a certain region. Deriving from Hippocratic origins, this theory was used to explain racial and national differences with regard to politics in ancient, medieval and early modern times. In the middle ages, the climate theory was increasingly linked to the Galenic theory of humoral complexion. Thus, the physical causes that are supposed to shape our characters or temperaments can be married with hereditary lines of explanation. Thus, northern Europeans and women counted as phlegmatic, jews and heretics counted as melancholic.
Now why does Hume reject this theory? On the face of it, Hume’s choice of explanation seems to run counter to his distinction between naturally superior and inferior races (see Eric Schliesser’s pertinent post). I can’t go into this now, but the climate theory seems to have way more resources for racist distinctions than an account based on education and sympathy.
Now whose version of climate theory is Hume rejecting? An immediate contemporary target might even have been Montesquieu who had tried to explain almost all social aspects through climate in his L’Esprit des lois, which came out in 1748, thus in the same year as Hume’s essay. However, Hume seems to appeal to a much earlier discussion for his rejection. Referring to Strabo’s Geographica (23 AD), Hume writes:
“Strabo, lib. ii. Rejects, in a great measure, the influence of climates upon men. All is custom and education, says he. It is not from nature, that the Athenians are learned, the Lacedemonians ignorant, and the Thebans too, who are still nearer neighbours to the former. Even the difference of animals, he adds, depends not on climate.”
Hume clearly sides with Strabo in declaring that custom and education are the crucial factors shaping our mentalities. In fact, one might say that Hume, paraphrasing Strabo, sums up his own philosophy in a nutshell. Strabo is quoted about 25 times and forms an important source for many of Hume’s historical considerations. What Hume’s Treatise brought to the table is a refined understanding of the transmission of custom through the mechanism of sympathy. But it is interesting to see that the perhaps central elements that, according to Hume, shape our whole mental lives, i.e. custom and education, are introduced in opposition to the climate theory.
What this leads me to is not an answer but a bunch of questions: What were Hume’s reasons for rejecting the climate theory, while contemporaries still embraced it? What version of the theory did he have in mind? And why did he, unlike Montesquieu, see it in opposition to custom? – At least the first of these questions might be answered with reference to Hume’s observation that people can display mentalities in stark contrast to what the climate and other physical conditions would have us predict. In his History, Hume writes:
“Even at the end of the sixteenth century, when every christian nation was cultivating with ardour every civil art of life, that island, lying in a temperate climate, enjoying a fertile soil, accessible in its situation, possessed of innumerable harbours, was still, notwithstanding these advantages, inhabited by a people, whose customs and manners approached nearer those of savages than of barbarians.”
Handling Ideas 