Science Fiction: What if...? or If this goes on...

Many years ago, in an intro to an SF book, the author suggested that there were two broad types or categories of SF. One asked "What if...?" and the other suggested that "If this goes on..."
I remember neither the book nor the author, but this idea has remained with me for a long time. It's a bit simplistic, but it is an interesting way to think about any particular story. And, it also provides a way begin to think about a story if, for some reason, one can't grab on to anything particular about it.

The "What if...?" story posits something unusual happening and then speculates on the meaning or consequences of that event. For example, "What if an alien spaceship should suddenly appear in the skies?" What would be the consequences of that occurrence? The answers to that question are many and varied, as numerous SF writers have demonstrated. Some writers would postulate that this was a hostile act with dire consequences for humanity, as HG Wells did in The War of the Worlds or as Larry Niven and Jerry Pournelle also suggested in Footfall, or as numerous other authors and film directors have done.

Other writers would suggest a different outcome, as did Harry Bates in his short story "Farewell to the Master" which became one of the best SF films ever made--The Day the Earth Stood Still. The aliens came, not to destroy humanity, but to warn them that its warlike behavior would lead to its destruction. In Arthur C. Clarke's Childhood's End, the aliens appeared because they were to act as the guides or mentors for the human race as it evolved into a higher level of being.

Other stories ask "What if..." about the discovery of faster-than-light travel or controllable extra-sensory powers or the collision between earth and a large meteorite or immortality or the destruction of the sun. Stories that are listed as alternative world tales are all in the "What if" category. What if the Germans and Japanese won WWII. Philip K. Dick's The Man in the High Castle is just one story that plays with that idea. I'm sure any SF reader could come up with numerous titles of stories that answer any of those questions, or questions that I haven't mentioned.

The other category, "If this goes on...," takes a different strategy. The author looks at something going on in society or the culture at that time and speculates about the consequences of this trend continuing and even strengthening over time. Fred Pohl and Cyril Kornbluth collaborated on several novels that would fit into this category. Their Space Merchants developed the idea of advertising agencies eventually becoming so powerful that they became the de facto government.

Over-population is another trend. Numerous authors have speculated on the consequences that might result if the human race continued to reproduce and spread over the entire planet. Harry Harrison's Make Room, Make Room is just one example of this. During the latter part of the 20th century, there was considerable discussion about multi-use buildings. Instead of developing building that were solely for residential use or business/commercial use, there was talk about buildings in which people could live and work and shop, and consequently seldom have to leave. Both Robert Silverberg in The World Inside and Isaac Asimov's Caves of Steel play with this concept.

However, a story that is placed in one category doesn't always have to remain in that category. A story written in the 1950s or earlier about a problem on a space station or during a trip to the moon would be science fiction, whereas today it would be considered an action oriented tale and probably not even shelved in the SF section.

Beginning in the 1940s, Isaac Asimov wrote a number of SF stories about robots. At that time, I would have placed them in the "What if.." group. However, now, in the 21st century, I would be very likely to place them in the "If this goes on..." category.

I wonder now about stories that are about longevity for humans--"If this goes on...?" Perhaps. But immortality tales would still belong to the "What if..? category. Right? Along with F-T-L drives or hyperdrives or warp drives or ESP powers and alien contact stories--benign or otherwise.