How to Create a Believable Magic System

ETA:  This is pretty much my most popular post, and I’ve come to the conclusion that’s because of SEO advantages such as a convenient titles as opposed to great content.  So an edit is in order.  I’m going to leave the original post unedited below, so feel free to read all the way down if you like.

One of the most common questions about writing fantasy is what to do about magic.  How do you create a good magic system?  How do you create a believable magic system?

What Do We Mean by Believable and How do I Accomplish It?

First, let’s touch on what we mean by “believable”.  A believable magic system in my view is one that allows the reader to maintain their willing suspension of disbelief. (Don’t feel obliged to read every single link if you know what I’m talking about.  PS, link one is to TVTropes.  Reader beware.)  There are several reasons why readers might give up their suspension of disbelief:

1. Deus ex Machina:  When your magic system makes things too easy.  As the third link above says, you get a certain amount of suspension of disbelief from your reader–I’ll call them confidence points, and you can use it up.  Especially by solving your main plot conflict by using your magic system in a way you haven’t shown that it can be used.  Your fire mage suddenly learning they can use water magic when that’s the easiest way out of the situation is a deus ex and it’s going to use up most or all of your reader confidence points.
2. Your magic is too easy.  There’s a common sentiment that magic requires a cost.  That’s often understood in the sense of mana points in a video game.   But there can be many “costs” to a magic system.  The important point is that your magic can’t just solve the plot problems for free or with little or no effort on the part of your protagonist.  Your cost can be in mana points if you want, or maybe it’s less concrete and logical such as losing an arm or a life.  Maybe you get a crippling migraine and can’t do anything for three days so you miss work.  But there has to be a trade-off.
3. Your magic only solves problems but never creates them.  In our migraine example above, Hero Protagonist misses three days of work and gets fired.  Sure, he got rid of the poltergeist haunting his little sister, but he had to pay a cost for it.  And in this case, that cost caused new problems even as it paid off his old debts.  Borrowing from Peter to pay Paul is a great way to price your magic.
4. Your magic is all powerful.  Not only does that seem pretty unlikely, it’s kinda boring.  Why am I walking halfway across Middle Earth if I can just nuke Sauron with a passing asteroid?  There are famous memes tackling this very question.  Similarly, why didn’t they just fly to Mordor on eagles?

 

So how can you make your magic system more believable for your reader?  It’s not that it has to be understandable in real world terms.  That’s not what we mean by believable.  After all, you’re writing fiction and we know magic isn’t real.  What you’re really trying to do is convince your reader that this is how things would turn out based on your description of how magic works.  Let’s try answering each of the complaints listed above:

1. Don’t do it.  Don’t let magic all by itself solve your conflicts.  You can let it solve part of your problem, but make your character use other tools, too.  Cleverness, for example.  Maybe you can cast an illusion or change the text of a document with magic.  But your character has to figure out what illusion or change to make.  Maybe your supporting characters can hold off the evil minions with magic, but your character still has to beat them in a sword fight.   Or perhaps your main conflict can’t be solved with magic at all.  Perhaps it requires persuasion, or compassion, or strategy.  And please, please, for the love of the fantasy genre… don’t have your magic do something that breaks a rule you’ve previously established for it.  This includes giving your character unique powers you’ve said your system doesn’t have, giving them a new power–especially with no foreshadowing–right at the key moment because otherwise they’re screwed.
2. Magic is too easy?  Make it harder.  You can put costs on it as I mention above.  You can make it take awhile.  You can require it to be prepared ahead of time like the old D&D trope of memorizing three spells at a time and forgetting them as they are cast.  Maybe it requires specific ingredients.  Maybe you have to learn a magical language or writing system.  Or complex magical theory.
3. Have your magic create as many problems as it solves.  This is a pretty common method for non-magical plot solutions, too.  You steal the artifact to trade for your dad, but now you’re a wanted criminal.  Like Nick Cage in National Treasure.  Or consider something like my migraine example above.
4. Limitations help to make magic believable.  After all, everything in real life has costs and or limitations.  You might be able to walk 20 miles a day.  A car can take you 600 miles a day.  But it can’t cross the entire planet.  A pallet jack in the back of Walmart can let you pull over 1000 lbs, whereas you can only carry 75 lbs.  But it can’t put them on the shelf, and you can’t take one home when you buy a futon.  Magic doesn’t have to work exactly like science or technology do on Earth, but if it can do anything you have to wonder why we’re not all living in palaces waited on by djinnis with zombies plowing the fields for us.  As an example perhaps your fire mage can manipulate fire, but they have to create the first spark through natural means.  If magic that can do anything isn’t believable, then all you have to do is not let it do everything.

Now, I realize these are general abstract principles rather than concrete suggestions.  That’s because the possibilities of magic are by definition almost endless when you consider all the systems together.  I can’t precognitively diagnose your specific problems without knowing what your system is and can do.

Scientific Magic Systems

To address the giant elephant in the room, one common way people have claimed you can make a believable magic system is by having a “scientific” magic system.  You can read that post if you don’t know what that means.  I’ve ranted a few times about the misunderstanding of what constitutes a scientific magic system, but the link above covers the gist of it.  This is one method, but it isn’t the only method, and it has its own problems.

Most “scientific” magic systems are not scientific but rather logical.  You list a few base premises, and then–in theory–by combining these premises the characters and the readers can figure out exactly what the system can and can’t do.  I discuss this at length in my post about The Inverse Law of Utility and Understanding.  The idea is that if your reader knows exactly what your system can do, they can be confident that the conflict won’t be solved by cheap tricks.  (A truly scientific magic system is slightly more complex and involves the idea of limited information, where we don’t have all the rules laid out for us.  Then the reader must make hypotheses, and seeing whether these turn out to be correct is one way to create believable tension.)

A logical magic system is a promise to your reader that you won’t undermine the tension of the story by solving your conflicts with cheap tricks.  They know the dire situation really is dire because by the rules of your magic system the protagonist can’t just wave their hands and say a few words and “Poof!” the bad guy bursts into flames.  Of course, there are two ways to deal with this.  One is to meet the readers’ expectations, and the other is to cleverly subvert them.  This is where a lot of logical magic systems fail to suspend the readers disbelief.  When they aim for subversion but actually just straight up cheat in the reader’s eyes.  It’s a tightrope.

A Metaphor!

And here I’m going to digress a bit.  A truly good magic system (or story) doesn’t rely on the reader to suspend their own disbelief.  It provides the harness itself and suspends the reader’s disbelief for them.  When the magic breaks a promise to the reader, such as that you can’t bring back the dead, it’s like cutting one of the ropes holding the bridge up over the chasm.  If you cut enough of the ropes, even if there are still some there, the bridge comes loose and drops the reader into the chasm of broken trust.  What makes for a really spectacular climax is when you drop the reader into the chasm but then at the last minute they find an intact rope to hang onto, restoring their trust and suspension of disbelief.  But if the rope you leave dangling for them is too slippery, they can’t grab ahold and still fall to their death.

The most basic answer to the question in the title of this post is that you establish trust with the reader by making promises with your magic/story and then keeping them.  If you promise a harrowing ride with death-defying leaps, it doesn’t really work out if the safety net below your characters is too obvious.

Conclusion

In the simplest terms, a believable magic system is one where the reader can believe what you tell them about it and one where they can believe that the story and the world it’s in really would turn out like this given what they know of how the magic works.  I haven’t addressed the latter point quite as thoroughly as I did the former in this post.  But it is a very important point from a world-building perspective rather than the story perspective through which we looked at the first point.  I hope to address it better in a later post.

I hope this time I’ve done a better job of answering your question.  For more concrete or specific suggestions for creating a sense of trust in the reader and then living up to it, please check out the “Magicology” page which links to all my posts on magic systems.

Original Post:

For the last two posts, I took a break from discussing magic to lay some basic groundwork on how stories function. To sum up:

Stories are kept interesting through conflict and suspense. These are created through tension.  Suspense is built through external “story” tension, and conflict is built through internal “character” tension.

If you haven’t read those posts, I suggest you do. But if you understand what I just said, you’re good to go.

How do you create a believable magic system?

The first step is to decide on your goals for the magic. Ask yourself these basic questions:

1. Does it create suspense? Perhaps the Dark Lord has the power to turn all the seasons to winter, and your characters are on the verge of starvation. Or maybe he can’t. But you as the writer must know which.
2. Does it create conflict? You know vampires? And all the angst that fantasy has decided comes with being one? That’s magic-derived internal conflict. But magical conflict isn’t only about whether Louis wants to drink blood or not. How would you feel if you couldn’t give your daughter a proper burial because that bitch Carnival had sucked her dry? Or what if the dragons are taking back their country dammit, and themselves take whoever is getting in their way.
3. Does it resolve suspense or conflict? For example, are your characters allowed to escape a situation by using magic? This is fireball country, people. Brutes or brains? Or both? Lavan Firestorm burned up an entire invading army that seemed destined to overrun Valdemar. And Dirk Proven saved the world by figuring out when the next eclipse would occur—and lying about it.
4. Does it create a sense of wonder? Who wasn’t impressed by the Nazgul, or Shelob? But I bet you don’t know where they came from, or how their power works. Good thing it didn’t matter. Now, Lackey’s ley-lines were fun, and you might even have wanted to be able to use them, but were they mysterious and awe-inspiring? No. Just a way to move along the plot. And there’s nothing wrong with that. But is it what you—as an author—want?
5. What themes will your magic express or explore? Yes, themes. I know you had enough of analyzing literature in high school. Or not. But whichever it was, this is still something you need to think about. Maybe you’re a panster, and you only know the themes after you’ve written the book. But they’re there all along, and it can be much simpler to follow them if you know what they are in the first place. Maybe you’re an environmentalist. Would you prefer a story about ghosts or trees that would rather not be cut down? What about the pollution of sacred sites? Ursula K. Leguin tackles this with the story of how one of the great cities used the Lips of Paor as a garbage dump. I bet they were really willing to help when our friend the Mender needed his powers temporarily removed.

Now that we’ve gone over choosing goals, maybe we should talk about how to achieve them. There are several things you need to do to make your magic meet your goals:

1. Know what your magic is and what it can do. Yes, flying is cool, but if your character is a water mage, there’s not much they can do about it. Making them a wind mage is not the solution, folks. The solution is to make compromises. Your character needs to part the sea in chapter 4? Then they can’t fly over the Mountains of a Million Trolls in chapter eight. If your character can do anything, we aren’t going to have much of a story.
2. Know what your magic is and what it costs. Maybe you can part seas and fly. But it’ll cost you your first-born child. And you’ve already got one. Maybe you know the character will pay for this later. But the reader has a much shorter attention span. The more you can do, the more—and sooner—it should cost you. Physically or mentally, it doesn’t matter. As long as it’s permanent at some point. You can trade the cost as many times as you want, as long as you don’t trade it out of existence.
3. Make it hard to learn. If your hero can learn the equivalent of a bible’s worth of spells in four weeks, why isn’t everyone and their pet hydra killing bandits and enjoying the magical equivalent of total climate control? If they are, then why does a prophecy about a fire-flingin’ half-elf princess so incredible to them? You’ve got to work out all the consequences. After that, it’s okay to indulge in some judicious ignorance.

Those are the basics, guys. There are way too any ways to create magic systems for me to fill out every little nook and cranny of magic-making theory. Later, I’m going to do some in-depth critiques of various magic systems, pointing out all the places things went right, and all the places they went wrong. And maybe I’ll even make up a magic system just for the Chimney, to really show you how the process looks. Field-work is fun, but “show don’t tell” is a real pain. Why do you think we writers don’t do it?