The difference between fantasy and science fiction

9 min readSep 17, 2023

Fantasy and science fiction often get pooled together as fantastic literature, which is not entirely inaccurate. Science fiction poses questions about our state of knowledge and the physical properties of the universe, which may be wrong at the current time. It's hard to draw a definite line between a logical and illogical unknown, especially when discussing the science of the far future. As Arthur C. Clarke said in his 1962 book Profiles of the Future: An Inquiry into the Limits of the Possible;

“Any sufficiently advanced technology is indistinguishable from magic.”

However, there is a difference between the characteristically science fiction story and the high-end fantasy, with much muddling in-between.

The science fiction story.

A science fiction story involves science as its basis or at least a logically constructed universe that operates on theoretically knowable and logically consistent laws. A scientific device, principle or political ideology is usually the nexus around which the story revolves. Science, in a real sense, makes the story happen. Drama and progression are derived from the application of the logical idea.

There are many classic examples of this. Tom Godwin's The Cold Equations (1954) is often heralded as a prime example where science produces a problem and point of drama. But, unusual for its time, science also declines to come up with a solution because, keeping within the bounds of logic, no solution can be found.

The basic premise is that a spaceman, carrying cargo between planets, is making a return trip back to the main ship. A girl has snuck on, hoping to see her brother. The excess weight of the girl means the ship won't be able to return with the fuel stored aboard and will eventually crash. The story also brings into play a sense of morality, as the cargo is a medical supply that could save thousands of lives. The story can only end with the girl being ejected into space. A similar story was presented in an episode of the classic British sci-fi series Blake's 7 (1978–82). However, additional weight onboard was discovered and removed, allowing both characters, Villa and Avon, to survive.

Other stories follow a more hopeful arc. Ross Rocklynne's The Men and the Mirror (1938) is part of a series following the adventures of Colbie and Devere, a detective and criminal, who chase each other throughout the galaxy. In this story, both happen to slide down a large convex radar dish while one pursues the other. The prime action of the novel is in the drama of the chase, but the story is really motivated by the scientific principle of kinetic energy and the laws of momentum. Unable to get to the top of the dish, both must work out a way to avoid the other whilst increasing their speed, lest they remain stuck at the bottom.

And so on. At the hard end, science fiction is replete with examples of a scientific principle or invention that drives the story. While the laws of physics are evidently in use in Jane Austen's Pride and Prejudice (1813), they never drive the story's action or cause a rift between Darcy and Elizabeth. Whereas Isaac Assimov's Robot Stories invent three laws of robotics, laws which each story in some way deals with. The laws are logical, if imaginary, so one set of actions can easily upset the delicately balanced rules of another.

I'll post the laws at the end of this article, but by comparison, Runaround (1941) poses conflicts with all three laws. A robot, impacted by the heat of a planet, is acting in contradiction to law three, the least important. Law one must be enacted to balance law three, as this is a more powerfully impressed law in the robot’s circuitry and will induce the robot to act accordingly.

In short, if a positive is being acted upon by a negative, changing the property to negative, we must add a secondary positive to regain the initial positive charge. The universe is always ordered and understandable.

Societal science fiction

The same principle can be seen in political science fiction, where the main focus is society and not primarily science. Again, Asimov perfectly married the two in his Foundation series, where societal progress and regress could be calculated based on enough evidence, using the method of psychohistory to calculate possible outcomes.

A typical example is C. M. Kornbluth and Fredrick Pohl's The Space Merchants (1952). Society has decided that capitalism is its greatest virtue, to the point where spending and earning overtake religion. If this is the novel's logic, we expect the surrounding world to reflect this attitude. And it does, to the extent that all actions in the book, the rise and fall of the protagonist, are determined by his societal status as a consumer. The novel's main activity is driven by the protagonist realising the true extent of his society and attempting to correct it in his own way.

Given X is true about society, then we can explain, logically, the progression of humanity.

The fantasy story.

The fantasy story is more directly linked with the mythic quest or adventure. It owes its origins to the likes of the tales of Gilgamesh, the labours of Herkules and Homer's Odyssey and so is far older, by comparison, to the hard-line science fiction story.

A quest or mission is set for the protagonist, who must go through steps to prevent a threat. Along the way, they meet with smaller trials, which are fantastical in nature.

The most perfect example is, of course, J. R. R. Tolkien's Lord of the Rings series, although this is more logical than the typical Greccian adventure tale. In a world of magic and mythical creatures, the protagonist and his friends must battle through minor skirmishes to defeat the greater force of evil. Likewise, a similar theme appears in other popular fantasy series such as Harry Potter, The Chronicles of Narnia, The Wheel of Time and The Golden Compass.

But an adventure alone does not make a fantasy. A fantasy is more simply a story where the logic of the world is not the principal focus of the story. X need not equal Y for Z to happen. Instead, a fantasy story is one in which things move beyond logic. The drama is derived from the character's reaction to the unbelievable rather than their exact approach. Whereas in a science fiction story, a logical process is used to overcome an obstacle, in a fantasy, the character's bravery, strength or magical ability is more in play. Their actions don't have to make sense, although their motivations should.

The Arabian Nights is a classic example of this. Fantastic happenings continually occur without deploying standard logic, but the character's motivation (either to get rich or stay alive) is recognisable.

Bram Stoker's Dracula (1897) is an example of fantasy with a logical underpinning. The vampire is a fantastic creature, and the methods of disposing of them aren't rational in a scientific sense. But the rules are rigid, in as much as garlic and sunlight will permanently harm a vampire, a fact which moves the story's plot along.

Other examples are, of course, plentiful. Lewis Carroll's Alice's Adventures in Wonderland (1865), The Oz Stories of L. Frank Baum, the Earthsea stories of Ursula K. Le Guin and Madeleine L'Engle's A Wrinkle in Time (1962) all employ nonsensical or at least unconventional logic whilst surrounding recognisable characters motivated by realistic goals.

I'm trying to explain here, via example, that the story's focus is different between fantasy and science fiction. The story focuses on a character's reaction to a fantastical event. The event itself is outside of standard logic, and the story's main thrust is the heroic quest, or journey, to overcome this event.

In science fiction, the event or logic puzzle is the main focus. Because of X, the logical events of Y occur, which leads to Z. Like a Chinese puzzle box, we must use our knowledge of the universe and any new knowledge present in the story to solve the science fiction puzzle or to arrive at a conclusion.

A healthy dose of mixing.

Of course, few authors set out to write under such stringent guidelines, even if most stories fall into one genre or another (and you can learn more about why that is in my other article here).

Most stories take from something else or 'leak' inspiration from another category. This is particularly true of science fiction because, as Clarke suggested, what we don't know may seem magical. A science fiction writer doesn't create the future; otherwise, they'd write nonfiction. They must guess what's not currently known or happening and assume certain unknowns.

But often, the line is blurred simply because the story is, after all, a story. An author may be attracted to the concept of a spaceship but wants to be free of the limits of genre. Instead, they want to create a world devoid of 'correct' or 'incorrect' assumptions. Most writers must think about the future (or know enough science to write with authority).

This has increasingly happened as science fiction staples, like the spaceship, become so common they no longer need to be explained. The spacecraft has become its own myth. We take it for granted in a story without knowing how it works.

So it's easy to see how we get hybrids like Frank Herbert's Dune series or Anne MaCaffery's Dragonflight series. Novels with some science that read more like adventure novels and aren't apologetic when they move away from the land of the real. These are more typical than the straight fantasy or straight science fiction because they both acknowledge our technical world and allow the author to play in a universe without limitations.

But don't say there's no difference between the genres. It's a scale with a dividing line.

Quickly, before we move on…

Before I finish, I'd like to touch on horror's relationship to fantasy and science fiction. Horror is a genre defined by the causing of a physical reaction, usually fear or repulsion.

Therefore, horror is neither fantasy nor science fiction but is a fear of the unknown. Dracula is horror as much as Frankenstein. Joseph Campbell Jr.'s Who Goes There (1938) is a horror because the creature is monstrous and unknown but is explained away and conquered by science. Many stories in the thirties and forties also took this tract, appearing horrified at the progress of science and exploration into the unknown.

But It by Stephen King (1986), or most of King's novels, are horror, although they're not science fiction. So, too, are the tales of Lovecraft and Poe (for the most part, both wrote science fiction). The prevailing emotion is essential, the subjective feeling the reader is meant to share, and not the story's logic.

I hope this clarifies things. If not, I've spent at least ten minutes of your time explaining things pointlessly. Let this stand as the real horror.


Here are the three laws of robotics;

  • The First Law: A robot may not injure a human being or, through inaction, allow a human being to come to harm.
  • The Second Law: A robot must obey the orders given to it by human beings except where such orders would conflict with the First Law.
  • The Third Law: A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.




A literary student by nature (and training), with a splash of ad experience, I’m setting out to make passion my career — reading, writing and SF.