The Principle of Minimum Necessary Information

Have you ever read a bad fantasy book prologue? Maybe it starts with a creation myth, only to go into the history of entire countries and important figures. Finally, it narrows down to the time and place that the book actually focuses on, and you get to chapter one.

Either that, or you’ve already given up and closed the book, wondering how all of that history could possibly be relevant.

The truth is, it’s probably not. Prologues are always fraught with danger, and never more so than in speculative fiction, where the author naturally builds up a rich and complicated world and history as part of the process of creating the setting. When you’ve gone to the trouble to create all that wonderful stuff, it’s so tempting to put it on the page.

Even if every single thing in that history-dump prologue is important for the reader to know, chances are good that it’s not all vital for the reader to know at the start of chapter one. It violates the Principle of Minimum Necessary Information.

The Principle of Minimum Necessary Information suggests that you should give the reader information only if it matters the story, and ideally right when the reader needs it.

Information, Just in Time

The history-dump prologue gives the reader more information than they need, long before they need it. If that info does matter later on, there’s a good chance they’ve already forgotten it, since they lacked the context to understand it in the first place.

One option for exposition that often gets overlooked is to simply tell the reader what they need to know, in straight exposition, at the exact moment it’s relevant. Too much of this starts falling back into history lessons, distracting from the flow of the story, but little bits sprinkled here and there can add context without too much distraction.

She is three stories up, ensconced in brick and mortar, almost a monument, her seat near the window just above the sign that reads “Hoegbotton & Sons, Distributors.” Hoegbotton & Sons: the largest importer and exporter in all of lawless Ambergris, that oldest of cities names for the most valuable and secret part of the whale.

“Dradin, in Love” – Jeff VanderMeer

It will slow down the story to take these little detours, so be careful.


A more subtle option is multitasking. This is when the text serves more than one purpose at a time. A description of a character’s surroundings as they travel is part of the action as it happens, but it might also reveal some of the history of the place that will matter later.

In The Return of the King, when Pippin and Gandalf first arrive at Minas Tirith, the city is described in detail.

For the fashion of Minas Tirith was such that it was built on seven levels, each delved into the hill, and about each was set a wall, and in each wall was a gate. But the gates were not set in a line: the Great Gate in the City Wall was that the east point of th ecircuit, but the next faced half south, and the third half north, and so to and fro upwards; so that the paved way that climbed towards the Citadel turned first this way and then that across the face of the hill. And each time it passed the line of the Great Gate it went through an arched tunnel, piercing a vast pier of rock whose huge out-thrust bulk divided in two all the circles of the City save the first.

Tolkien isn’t afraid to spend a good page or two describing a landscape, and this description of the city goes on for several paragraphs, but it does serve double-duty. First and foremost, this is exactly the awe-inspiring view Pippin sees as he approaches this last great city of men in Middle Earth. However, this will also be the site of an epic battle, and one where Pippin and Gandalf will find themselves racing around under dire circumstances.

By describing the city in detail on Pippin’s first viewing, Tolkien captures the majesty of what he’s seeing in a relatively quiet moment. Later, in the rush of battle, when the pace is fast, we already understand the layout of the city. Tolkien doesn’t need to interrupt the action to describe the characters’ routes.

Clue the Reader In

Even further away from straight exposition are clues and hints. Some stories just contain ideas, events, or settings that are complicated, requiring (and deserving) extensive description. Instead of springing them on the reader all at once, it can pay to lay some groundwork.

By layering small clues here and there before the Big Event, the reader has less to take in when it arrives. This is akin to multitasking, but spread out in little bits beforehand. Once again, when done well, it’s seamless and the reader doesn’t even realize that they’re catching fragments of something that will be fully revealed further on.

Make it a Mystery

If a character has good reason to be missing the same knowledge as the reader, they can act as a reader-surrogate. In that case, the missing knowledge can be treated as a mystery. The story doesn’t need to be a mystery story, and the mystery itself doesn’t even have to be a major driving force in the story. It might only be a very minor goal of the character to find the answers to their questions.

The great thing about couching exposition in mystery is that it stops being a chore that has to be cleverly imparted to the reader without slowing down or distracting from the story. Instead, it becomes a little treat, a tiny reward for the reader and the character, when they find out what’s going on.

There’s a reason the outsider-as-a-proxy-for-the-reader is so often used: it’s a very effective way to impart information. Just be aware that this frequently-used pattern can easily become tropey. The mystery has to make sense within the story. If it’s shoehorned in as an excuse to throw some exposition-as-mystery at the reader, it can backfire horrendously.

Keep it to Yourself…For Now

What if you just don’t tell the reader?

No, seriously. Sometimes the reader just doesn’t need all the context for what’s happening. Yes, it’s going to be a little confusing. But if the story is compelling, the reader wants to keep reading. They’ll accept that they don’t understand something, at least for a while.

This “suspension of comprehension” can work, but it incurs a debt. The reader will be slightly confused while they keep reading. If that confusion is resolved by an explanation later on, the debt is paid. If more confusion is layered on, the debt grows. If it grows too high, the reader will decide that the story makes no sense and give up. Every reader is different, but most have their limits.

This is a tactic that readers of speculative fiction are more used to. Sci-fi and fantasy often involve elaborate worlds that are wildly different from the place we live, and readers of these genres understand that the setting will unfold over a large portion of the book, simply out of necessity. Readers of other genres may have less patience for this style of ongoing world-building. This is a case where the genre your story is marketed under can make a difference in reader expectations.

Principle, Not Law

Exposition sometimes get a bad rap. It’s easy to put in too much of it, but that doesn’t mean it can’t be used carefully and sparingly. Still, when you have a lot of info to get across, don’t just dump it on the page. Remember the Principle of Minimum Necessary Information. Give it to the reader when they need it.

Author: Samuel Johnston

Professional software developer, unprofessional writer, and generally interested in almost everything.

3 thoughts on “The Principle of Minimum Necessary Information”

  1. I am reading a Margaret Atwood book. She is SO good at multitasking. The characters and setting are bland. (It’s The Edible Woman.) And the action is slow. But there’s a sense of dread building up, and I think it’s from her careful choice of words in the descriptions and in the main characters internal dialogue. I’m loving the book, about 60 percent through it.

    Liked by 2 people

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