I recently read Childhood's End (1953) by Arthur C. Clarke. You know Clarke, he's the guy that said "Any sufficiently advanced technology is indistinguishable from magic." As a famous SF author, you'd think his novels would always advocate science, technology, reason and the like. This is definitely not the case in Childhood's End. Very briefly, the story involves aliens coming to Earth and what ultimately happens to human beings.
The reader gets the first inkling of Clarke's anti-rationality/anti-science theme when “the fall of religion had been paralleled by a decline in science…the heart had been taken out of fundamental scientific research..." The novel takes a decided turn towards irrationality when the reader meets Jean, who “...really seemed to think that there was something in this business of telepathy and second sight." The aliens claim "...she may be the most important human being alive." Toward the end of Clarke's story, the Overlords' suspicions are proven correct and Jean's children transform into something else--the next stage of humanity.
In the big climax the Overlords explain what happened to the humans: “Science, it was felt, could explain everything…Yet your mystics, though they were lost in their own delusions, had seen part of the truth. There are powers of the mind, and powers beyond the mind, which your science could never have brought within its framework without shattering it entirely. All down the ages there have been countless reports of strange phenomena—poltergeists, telepathy, precognition—which you had named but never explained….they exist, and, if it is to be complete, any theory of the universe must account for them. …your scientists began to investigate these matters. They did not know it, but they were tampering with the lock of Pandora's box. The forces they might have unleashed transcended any perils that the atom could have brought. For the physicists could only have ruined the earth: the paraphysicists could have spread havoc to the stars." Thus, paraphysicists trump physicists, and the irrational trumps the rational.
Wowsa! What a bizarre theme for a SF novel! Apparently anything goes when it comes to SF.
So send us your irrational or rational SF, Fantasy or Horror stories! :)