Sanderson’s Third Law: When Should You Create a New World?

If you’re constantly coming up with new story ideas, you might also come up with a lot of different settings in which to set those stories. The question is, at what point is it appropriate to create a whole new world and when should you just build on whatever you already have?

Sanderson’s Third Law of Magic states,

“Expand what you already have before you add something new.”

Now, these are Sanderson’s Laws of Magic. He has magic systems in mind. But this one, at least, is applicable to much of writing and today I want to explore how it interacts with worldbuilding as a whole.

Why to Expand First

First off, why is Sanderson’s Third Law good advice for worldbuilding as a whole?

For one thing, it makes worldbuilding a lot easier on you as the author. Would you rather have to juggle seventeen completely separate worlds, none of which are very deep; or would you rather have three or four worlds that encompass several more specific settings which interact with one another and lend depth to their home world as a whole?

Fewer worlds are easier to keep track of and make it easier for you to keep your worldbuilding notes together. One binder that contains several settings and the ways in which they’re connected is easier to keep on hand than several notebooks about entirely separate settings.

Now, in some ways it is more complicated to connect your worlds. When you connect settings, you do then have to develop how they interact and impact one another, which can supply its own challenge. However, I’ve found that in the end connecting settings not only simplifies things but also forces you to exercise your creativity in problem-solving as you develop those connections and interactions.

Connected worlds are also fun for your readers down the line. It’s a lot of fun, as a reader, to spot a cameo mention of another story or character as you’re reading one of an author’s works. (Hannah Heath’s Torn Universe is very well-done in this area, among others.)

Essentially, expanding on what you already have is simpler, fosters more creativity, and can be more fun.

When Expanding Works

When deciding whether or not to create a whole new world for a particular story, the most crucial consideration is what your purpose is for a given world. What particular tone do you want to maintain with this world? What sort of themes do you want to explore through it?

To use my worlds as an example, each has a particular focus point. Esleon is designed to be a futuristic, fantasized version of Earth, which gives it some limitations. Aleruus is, at its core, a classic Medieval fantasy world; it has elements that set it apart, but all of its pieces have to align with a classic fantasy tone. Deseran, meanwhile, is primarily an exploratory world; I can explore all sorts of cultures and concepts in Deseran, which makes it easy to add to and tie new ideas into.

If I come up with a culture of nocturnal elf-like beings with advanced technology, that could go in Aleruus, but it fits better with Deseran. There’s no way it would fit in Esleon. Whereas if I want to explore real-world homesteaders in a world they’ve been able to shape to suit them, it’s not difficult to adjust Esleon to support that. If I want to write about vampires in Gothic London… Well, that does genuinely warrant its own, separate world.

But so long as your new concept works with the purpose of one of your existing worlds, it’s likely best to tie it in with what you already have. It will not only give you an easy place for this new concept, but it ought also to help fill out the tone and purpose of the world you tie it into.

When Expanding Doesn’t Work

All of that said, there are times that it doesn’t work to just expand on what you have. As Sanderson says, “Expand what you have before you add something new” (emphasis mine). Just because expanding on what you already have is the first step doesn’t mean there’s never a place for adding something new.

There are generally two reasons you might want to create something new rather than expanding on what you have. First, like I already touched on, you’ll want to create something new if your new idea truly doesn’t suit anything you already have. If your idea would undermine the tone or purpose of your existing worlds or just doesn’t fit, it’s time to add a new world.

Maybe vampires in Gothic London can be finagled to fit with Esleon’s “magic” system… but the tone is all wrong and it would alter the overall idea of Esleon for readers. Sometimes just because you can doesn’t mean you should. When considering whether or not to connect settings, your core question ought to be “Does this support what I already have?”

The other reason would be if your new concept requires so much adjustment that it would alter firmly established pieces of the world you’re looking to add to. For example, if you already have a novel set in this world and adding this new concept would drastically change the worldbuilding established in that novel. Now, sometimes it’s still better to make the changes; sometimes they strengthen the world and/or the stories set there, and so the changes are worth it. But there should be a lot more thought involved if you risk changing a lot. And if you’ve published a story in the world… changing established worldbuilding elements is usually not a good look.

To Expand… Or Not to Expand?

You’ve asked if your new idea suits a world you’ve already created. You’ve determined whether or not it supports the tone and themes you want to focus on in that world. Now it’s up to you. Will connecting this idea to an existing world simplify things or make things over-complicated? Will it support your themes or undermine them? Only you know the answer to those questions.


Do you tend to connect your setting ideas, or create many separate worlds? Which have you found to work better for you? Do you have a favorite of your settings or cultures?

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