Fantasy and Science Fiction

Two genres of the impossible, divided by how they justify it.

Both genres depart from the world as it is. They differ in how the departure is justified. Science fiction extrapolates from natural law, offering a technological or scientific account. Fantasy posits a different set of rules and asks the reader to accept them.

World-building terms

• Speculative premise — the single change from our world.
• Internal consistency — rules that hold once established.
• Exposition problem — conveying the rules without stopping the story.