Once you start looking for counterfactuals, they start appearing everywhere. In reading Anthony Pagden’s new book, The Enlightenment and Why It Still Matters, I came across a fleeting quotation from Jean Jacques Rousseau’s treatise, A Dissertation On the Origin and Foundation of the Inequality of Mankind (1754) that revealed a counterfactual basis for the entire enterprise. I went back to the original document, portions of which I regularly teach to undergraduate students in my Western Civilization course, and found that, indeed, the philosopher premised his text upon what is clearly a self-consciously counterfactual foundation.
Rousseau begins notably by explaining his decision to set his analysis in a “state of nature,” a much-loved setting of other Enlightenent thinkers who were eager to develop what they optimistically called the “science of man.”
He writes, “Let us begin then by laying facts aside, as they do not affect the question. The investigations we may enter into, in treating this subject, must not be considered as historical truths, but only as mere conditional and hypothetical reasonings, rather calculated to explain the nature of things, than to ascertain their actual origin.”
In other words, Rousseau admits that his entire essay will employ a form of speculative reasoning.
He then comes to the main counterfactual: “Religion orders us to believe that God Himself took men out of the state of nature immediately after the creation and that they are unequal because He wanted them to be. But religion does not forbid us from forming conjectures…concerning what the human race could have become if it had been left to itself. That is what I have been asked and what I propose to examine in this Discourse.”
Challenging the Biblical story of the expulsion from the Garden of Eden, Rousseau wants readers to imagine human development as it would have unfolded outside of divine punishment -- a premise as secular as it is counterfactual.
I am unsure how common this kind of historical counterfactual thinking was in the 18th century. But it certainly has retained its viability as a mode of setting up thought experiments to prove analytical points.
Just for fun, it’s also worth noting that Rousseau used other counterfactuals to hypothesize about the nature of “savage man.” For example: “The body of a savage man being the only instrument he understands, he uses it for various purposes, of which ours, for want of practice, are incapable: for our industry deprives us of that force and agility, which necessity obliges him to acquire. If he had had an axe, would he have been able with his naked arm to break so large a branch from a tree? If he had had a sling, would he have been able to throw a stone with so great velocity? If he had had a ladder, would he have been so nimble in climbing a tree? If he had had a horse, would he have been himself so swift of foot? Give civilised man time to gather all his machines about him, and he will no doubt easily beat the savage; but if you would see a still more unequal contest, set them together naked and unarmed, and you will soon see the advantage of having all our forces constantly at our disposal, of being always prepared for every event, and of carrying one's self, as it were, perpetually whole and entire about one."