"Science fiction ...as a genre... differs from fantasy in that, within the context of the story, its imaginary elements are largely possible within scientifically-established or scientifically-postulated laws of nature (though some elements in a story might still be pure imaginative speculation). Exploring the consequences of such differences is the traditional purpose of science fiction, making it a 'literature of ideas'. Science fiction is largely based on writing entertainingly and rationally about alternate possibilities in settings that are contrary to known reality." (from wikipedia)
So, it's a "literature of ideas"?
Common science fiction themes extrapolate world issues of the present and their possible consequences into future societies.
To me, it's a genre that explores "what if" - what if violence did erupt on a global scale as we've feared? what if there was peace on earth for centuries in a society, however flawed, configured to allow exploration of humanity's more spiritual side? what if 'exclusivity' claims were forbidden and all religious paths were offered equally? would this change the way we view our belief systems? would a generation come with abilities that we can only imagine? could we finally live in freedom without violence?
Since this genre has taken off, and exploded into so many 'sub-genres', many books deserve their place amongst the classics. For me Isaac Asimov, Frank Herbert, and John Wyndham stand out as key influencers for this story.
At the top of my list of scifi legends is Isaac Asimov and his phenomenal Foundation series. In first falling in love with SF, I had to exhaust this original master before moving on. Frank Herbert’s Dune books were equally enthralling. I mention John Wyndham as well because “The Chrysalids” has some elements in common with “Vision Speak”. (both take place after a world cataclysmic event, with main characters experiencing extrasensory abilities in a restricted society/dystopia). In fact, all of these authors (and many science fiction works) explore these themes. Science fiction isn’t just about aliens and space ships – so much of it is trying to sort out where we’re going and how the human condition will evolve.
Other science fiction novelists are too numerous to mention but recently, I've been enthralled with stories by Orson Scott Card, Robert Sawyer, and "The Sparrow" by Mary Doria Russell.