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While I explore this site, I occasionally see the phrase "GM fiat" (or "DM fiat", for D&D questions and answers), but I don't know the exact meaning of that. I want to know the meaning of that terminology.

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A fiat is an order, or decree, by someone in authority. I hope that makes the phrase clear; it's not actually a roleplay-specific term. (So I'm not answering, because I suspect this question really belongs on English.SE.) – Tynam Jan 22 '14 at 0:20
@Tynam I don't think is in a position to talk about the narrative and social authority of the GM in RPGs. – BESW Jan 22 '14 at 0:24
This is fine and on topic. Look under the heading "This is not the right site for questions about" in our on topic help, where we have a guideline for whether real-world topics belong here or elsewhere: an RPG expert would give a better, different, and more specific answer than an English expert, and four of us have in fact done so. From an RPG context, this is an entirely appropriate place to ask this question. – doppelgreener Jan 22 '14 at 12:46
Mod agrees. Please proceed with answers. – mxyzplk Jan 23 '14 at 1:15
up vote 34 down vote accepted

In a large number of RPGs, the GM is positioned as the controller of the world, its NPC inhabitants, the items in the world, and their essential natures. They are also often positioned as the final arbiter of rules, and thus hold considerable authority. Hopefully, a GM imbued with such power will remember: with great power comes great responsibility.

That said, a fiat is defined as:

  1. an authoritative decree, sanction, or order
  2. (irrelevant)
  3. an arbitrary decree or pronouncement, especially by a person or group of persons having absolute authority to enforce it

So a GM fiat is when the GM says something is the case - because they have the authority to do that - and it becomes the case.

A GM fiat is produced independently by the GM. It is separate to decisions made by the group as a whole: a GM can declare a house rule as a GM fiat, but that's different to the group producing a house rule together.

Implicitly, the GM is not required to justify or explain their fiat - these things just happen because you're the GM and get to make them happen.

Because GM fiats are arbitrary and can involve major changes (like the changing of the rules themselves), the motto of "with great power comes great responsibility" is massively relevant. These changes could make the game more fun or extremely un-fun for players.

Some examples of usage of GM fiat

  • Create your own fluff for in-game races, civilisations, etc, which may either add to or replace lore from the books.
  • Create new material in the universe, such as:
    • New items which don't exist in the game's rulebooks.
    • New planes, gods, and so on. A fellow member of this site once played in a game where all bags of holding lead to their own demiplane, with a Demigod assigned to guard all such demiplanes.
    • In D&D, create a Freezing Hands spell as a cold equivalent of Burning Hands, and give it to one of your players or NPCs.
  • Make a declaration about how a certain rule works, especially for clearing up ambiguities.
  • Make rulings where there is no clear rule.
  • Declare that something simply happens when there is no clear justification for it.
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Fiat comes to English from the Latin Fiat, which is the third-person passive subjunctive of Fiere (to do), basically meaning "Let it be done".

It is used in English usually to mean a decree or judgement, so a "GM Fiat" is essentially a way of saying "The GM says this is the way it is, so this is the way it is, no arguments."

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+1, Short and to the point. – GrandmasterB Jan 22 '14 at 17:14

Fiat in Latin means "let it be" or "let it be done". It roughly means to make a decree.

DM/GM Fiat in particular is generally considered the act of a GM arbitrating things not covered by the rules, declaring house rules or creating a rules clarification that does not exist in the pre-written material.

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Fiat: by decree.

In the context of gaming, GM Fiat means, literally, "because the GM says so."

Anything more is context dependent.

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DM Fiat often goes along with what is also known as Rule Zero: The DM's judgement is final and supercedes all other officially documented rules. Essentially, they have the ultimate authority, and can make any decision they wish without being able to be overruled. As with any such dictator-like power, this can be used for either good or ill, but has become most famous for the worst of examples, such as with DMs making abusive or simply foolish decisions.

This rule can be considered inaccurate, however, and an additional term has come to represent this fact: Rule Negative One: What the gaming group as a whole agrees upon is final and supercedes even Rule Zero, because if everyone is unhappy, then they will leave and there simply is no game. It's useful to remember that a DM can not truly bully the players, because it is just a game, and everyone can just opt to not play with them; perhaps go play a new game with a new DM that doesn't make such abusive fiat decisions.

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I am not sure it's actually helpful to talk about Rule Zero, because that concept only exists in a handful of RPGs (and within the D&D community). In other games where something like it exists, it is often a different concept or goes by a different name. Rule Zero itself is far from universal. (I don't wish to upvote because I don't even really want to acknowledge these two 'rules') – doppelgreener Jan 22 '14 at 15:07

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