Why didn't you mention this 'reasonable' requirement of the hope in the initial post?
It was one of a billion things I didn't talk about.
Here is what I said, in the "initial post":
when it comes to "declaring actions" in RPGing, the key question is who gets to decide what descriptions of the PCs' actions are true, and how.
It's true that some players are content with getting to decide only very "thin" descriptions, focused on the character's bodily movements (analogous to Davidson's "I flip the switch"), like I attack the Orc with my sword or I wink at the maiden or I hide from the soldiers in the barn or I bring the child into the Tiny Hut. But many players want to have some influence over the truth of "thicker" descriptions of their PCs' actions, like I kill the Orc with my sword or I soften the heart of the maiden with a wink or I avoid confrontation with the soldiers by hiding in the barn or I rescue the child, first by providing shelter in the Tiny Hut.
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If players were not intended to have some influence over how their actions are resolved, and the outcomes that follow from their PC's bodily motions - which is to say, if players were not intended to have some influence not only over the truth of then descriptions but also over the truth of thick descriptions - then why would their be action resolution mechanics at all?
When the player declares "I pick the lock", then - as you say - there will almost always be some other description, beyond "the lock is now open", that they hope to become true. Its failure to become true would be an in-fiction consequence of the character failing to pick the lock as they hoped.
This post is not mysterious, nor especially complicated. It says that:
*Some players are content with getting to decide only very thin descriptions, focused on bodily movements (like "I flip the switch" or "I (try and) pick the lock");
*However, many players want to have some influence over the truth of "thicker" descriptions of their PCs' actions (and, as a special case of this, when a player declares "I (try and) pick the lock" there will normally be some other, "thicker", description that they hope to become true);
*If players were not intended to have some such influence, then action resolution mechanics would be largely unnecessary (eg if all the player can influence is "I move my lockpicks in the lock, so as to try and pick the lock", then the GM could just make up the rest);
*The failure of a hoped-for "thicker" description to come true would be an in-fiction consequence of the character failing to do as they hoped.
These are general propositions about RPG play: about what many players hope to achieve via their action declarations, and about the rationale for having action resolution mechanics. As I've repeatedly posted now, they say
nothing about what sorts of descriptions are permissible in the context of action declaration, and will factor into action resolution. That's not what the post was about.
So I agree, but why does the hope need to be reasonable?
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How is it determined what counts as a permissible action declaration? The System?
I don't know what you mean by "the System". If you mean
this - "a means by which in-game events are determined to occur" - then the answer,
yes, the system determines permissible action declarations, is tautological.
If you mean "the published rules" then the answer is,
it will depend on the rulebook. Some published rules discuss what is or isn't a permissible action declaration (eg 4e D&D does, in its DMG; Burning Wheel does; HeroQuest Revised does), but many don't (eg I don't think Classic Traveller, or AD&D, ever discusses this; Moldvay Basic touches on it, a bit obliquely, in chapter 8).
My view is that if a group of people trying to play a RPG together
can't come to agreement on whether or not a player's would-be action declaration is permissible, then they have a pretty big issue. But as I wrote in the previous paragraph, a lot of rulebooks leave it up to the group to resolve this issue.