Telepathy (and similar terms like "psionics", etc.) is found throughout science fiction, but seems to be particularly a part of many, many Golden Age stories and novels.
In stories that otherwise seem to be understandable extrapolations of science as it was understood at the time, telepathy seems to be magic that was thrown in. From my vantage point in 2017, the idea that the future would include telepathic powers seems bizarre. Yet, for many Golden Age writers, it seems to be taken as a given.
It seems apparent that I'm missing some cultural context about how either science or pseudoscience thought about telepathy during the Golden Age. What culturally was happening during the Golden Age of science fiction that meant that in ostensibly "scientifically" minded stories, psychic powers were a regular aspect?