A E van Vogt's "War of Nerves" (novelette, space opera, free): Cultures reach an _inferior_ stage, & then forever stay there!
How one reads the subtext, however, depends on reader's own prejudices. The key thesis of the story is: cultures eventually fall, a stage author calls "fellah". Once in fellah stage, a culture forever remains there. And all individuals comprising the culture suddenly turn into inflexible idiots - hence easy pickings, even individually, for anyone from a more vigorous culture! Since India is specifically named a "fellah" culture in the story, I'm obviously biased in how I take the thesis.
- Aliens in the story are "hymenopters" - apparently, beings that grow a copy of themselves from their body - on the outside rather than inside; copy later detaches to become a separate individual.
Fact sheet.First published: Other Worlds, May 1950.
Download full text as part of the scans of the magazine it originally appeared in.
This story is part of author's "Space Beagle" series.
Related: Stories of A E van Vogt.