Brad Delong notes that speculative fiction forms the basis of much more than fiction.
Back in 1759, the man who was to become the first economist, young Adam Smith, a Scottish moral philosopher on the make, wrote in his Theory of Moral Sentiments of how “a stranger to human nature, [seeing] the indifference of men about the misery of their inferiors . . . [would conclude that] pain must be more agonizing, and the convulsions of death more terrible, to persons of higher rank, than to those of meaner stations.”
There is no such alien stranger. Smith is telling us of somebody who does not exist. It’s a very short, eighteenth-century science-fiction story. Why? Because we love to tell one another false stories, to converse about imaginary people, be it in philosophical treatises or in television serials. It is what we do as humans.