"[A] group of small city-states seems to be the best environment for genius. That was the situation in Greece during the Golden Age, in Italy during the Renaissance...."
The quotation is from The Black Flame, a science fiction novel by Stanley G. Weinbaum, written in the early 1930s. Does a broad view of the history of human achievement tend to bear out this contention or is it a fallacious generalization buttressed by cherry-picked examples?
^(PS-Just in case the style of the question makes it sound like an essay question for some test: it's not. I've recently been reading this book, by a largely forgotten writer who died tragically young, and the sentence piqued my interest. Lacking the broad knowledge of history required to properly assess it, I hope that one of the many erudite and well-spoken souls of /r/askhistorians can lend me the benefit of his wisdom.)
^(PPS I suspect my tone in this post is oddly literary or flowery or something in that vein. Just something that happens to me sometimes when I read a book with a distinctive literary style—it tends to infect me. Please forgive any concomitant oddity about my prose.)
I mean, it's true that certain collections of city-states have produced periods of significant cultural and scientific progress. Although I honestly have no idea what "all over the world before the Second Enlightenment" means. But there are too many counter-examples for this to be an outright rule: for one thing, China and the Arab world have never been at a point where they could be described as "a group of small city-states," yet they seem to have been good environments for genius at least some of the time. Too many large empires, or even modern nation-states, have enjoyed periods of significant scientific and cultural leadership for us to conclude that something about the city-state model just unlocks the potential in its citizens, or something. What actually produces the 'best environment for genius' is an extremely difficult question, since it's not necessarily clear what 'genius' means or what the 'best' environment for producing it would be.
It's a subjective observation. What is a genius? How does one falsify this observation? How many geniuses does a metropolis need to produce before it's a good environment for producing geniuses?
I would point to the Islamic "Golden Age" as an example of incredible genius being produced in huge sprawling empires.
Was the genius of Rome somehow less than that of the Greek city states?
It just doesn't seem to me to be the sort of question historians ask or are capable of answering. I frankly don't see any possible connection between the exercise of sovereignty by small poleis in close proximity as having a bearing on the intelligence or intellectual production of its inhabitants.
I think there could be something more compelling to Orson Welle's famous line in the Third Man about conflict producing innovation, so insofar as such states might be more likely to fight there might be something to that idea.
I think it would be important to note that the political structure created from "city-states" or "like city-states" can not be held directly responsible for the creation of suitable environments for geniuses.
For instance, the McNeills in their book, "The Human Web" (micro-history, if I recall correctly) argue that the rise of higher thinking was due to the absence of authoritative religious bodies and priesthoods. Of course, it wasn't the sole reason, but it certainly allowed a lot more higher thinking, outside of the realm of theology and religion.