First, we start with reality unless the story tells us otherwise. If a story mentions a human walking into a room, we assume humans breathe, have bodies, experience gravity, and can be harmed. The fiction does not need to rebuild reality from scratch. It borrows reality as its default background, then changes what it needs to change.
Second, we measure the story against reality. We let reality push back. If a fictional character falls from a cliff and survives, the story owes us an explanation: a miracle, a safety net, a dream, a superpower, cartoon logic, or bad writing. Without some story-world reason, reality still sets the expectation.
Stacie Friend argues along these lines. She challenges the common idea that fiction is simply opposed to fact. Fiction is not cut off from reality. It is about reality, even when it asks us to imagine reality differently. That means fictional truth does not float in a separate metaphysical bubble. It depends on how the work guides our imagination against the background of the real world.
The basic rule is simple:
Real-world truths carry into a fiction unless the work excludes them.
This is the fiction is constrained by reality idea, which adds that fiction departs from fact without escaping reality.
That is why we can understand fictional worlds so quickly. We do not need the author to tell us that people have parents, cities have streets, fire burns, or death matters. We bring those facts with us. The story then tells us where to adjust: dragons exist, ghosts speak, time travel works, or one detective can solve impossible crimes.
In TST, this supports the idea that fiction is constrained by reality. Fiction departs from fact without escaping reality. It rearranges real-world materials: bodies, emotions, danger, memory, desire, power, loss, hope, and consequence. The story may be invented, but the background it leans on is real.
So, how do we know what is true in a fictional world? We begin with reality, follow the story’s changes, and test each claim against the world the fiction builds. Fictional truth emerges where real-world background and story-world invention meet.