How does Fate handle wildly out-of-scope attempts to declare story details?

Question

The way I see, Fate lets anyone declare details and describe parts of the world more or less as the player sees fit. Unless the setting is based on a certain fixed universe known by all players, someone may decide to declare a detail that is not suitable for the setting in question (for example: magic spells in a clearly non-magic world, existence of a certain divinity a cleric draws power from...).

Is it possible to reconcile a "closed/fixed world" where the setting is as it is predefined by the GM (or other) and Fate system? Can the GM (or the player responsible for the setting) unilaterally deny actions that have no place in that specific world, must it be a majority vote or should the table arrive to a consensus?

Answer 1

Someone trying to declare an out-of-scope story detail with a Fate point is handled pretty simply: justification is needed, and the GM can veto. Summarising the relevant parts of the Fate Core section on fate points:

1. The player should be able to justify the story details by relating them to existing aspects. (Usually this is a no-brainer; of course declaring the forest has a fallen tree in it is justified. We only explicitly discuss this in my group if it's necessary, like if someone has to ask how something makes sense.)
2. The GM has "the right to veto any suggestions that seem out of scope or ask the player to revise them, especially if the rest of the group isn’t buying into it."

The same principles apply to declaring facts about the world via actions, such as create advantage. These are about what your character can do in the fiction, and if your character doesn't have a justifiable way to discover or reveal that magic exists (and be correct), an attempt to do so could be vetoed as unjustifiable. The group can talk about whether they seriously want to do this stuff, of course, and do it.

Unofficially, if the GM were declaring such a detail, and the players didn't want it, they could veto it — this is an above-the-table discussion, the likes of which Fate actively encourages. It's a "hey, don't do that, please" conversation. The GM, being only the first among equals, should listen.

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Coherent settings are usually created in pre-game discussion, and refined and reinforced throughout your play time. The players talk at the beginning about the kinds of setting they wish to play in, what time period, what the game's focused on, etc. If you're playing in a Fate World or a game like Atomic Robo RPG, these details are probably already mostly established (but open to modification). These conversations set the game expectations about what's in and out of scope. The GM can veto attempts to break the established boundaries if the group isn't keen on it, and the group can have a conversation when a not-firmly-set boundary appears challenged.

Answer 2

The part about "how does Fate handle wild-ass Declarations" has been answered, but regarding the questions about how locked-into-stone Settings are:

"Is it possible to reconcile a "closed/fixed world" where the setting is as it is predefined by the GM (or other) and Fate system?" Of course. There's no conflict. Fate gives you a way to get on the same page about the world before play starts. If you aren't doing "game creation" like in the second chapter of Fate Core, you still need to have a group who's on the same page about the game and its setting and world. Personally, I recommend a "Session Zero" for any game, even if it's using published setting and adventure material, like a Fate World. If it's a one-shot, the GM does have a lot more responsibility as well as permission to establish things.

"Can the GM (or the player responsible for the setting) unilaterally deny actions that have no place in that specific world?" Of course (see rule cited in doppelgreener's answer). The GM should be prudent - if it's unilateral and it's against unanimous, vocal support from all players present, that might not be the right choice.

"must it be a majority vote or should the table arrive to a consensus?" To Declare a Detail? Probably not, but Maybe. Especially if it's not a Detail but it's actually a Setting Element. This should have happened before roleplay started. During Session Zero, when you're all following the Game Creation and Character Creation chapters, or else reviewing the gamemaster's published or otherwise pre-defined material. So that it isn't a disruption in the middle of a session.

Here's the thing: The Declare a Story Detail rule should be used for points of plot, not for establishing world/setting facts.

It's the difference between spending a Fate point on "Since my character is retired from the Academy, it makes sense that the Academician who just got called as an expert witness has cited my work. So, can we say that my lawyer can argue that she's not impartial by using that fact against her and discredit her testimony? offers Fate point" and "holds out token Here's my Fate point, let's say that all I have to do to escape these orbital patrollers is put my starship into Hyperspace... Yeah, we really need that in this universe anyway..."