It is IF the DM leads the players into believing that they are the ones establishing these details, when in fact they are not.
If/when the players think that certain details are established by their actions but, actually, they are determined by the DM regardless of what the players do - that's railroading.
If we're just talking about setting details the players have no part in? Setup, worldbuilding, things established before the players even get it it - stuff like that? No, that wouldn't have anything to do with railroading.
Yes, that's basically what I'm talking about. I don't think there is disagreement here.
I cannot find the original post that asserted the thing I wanted to respond to, so I am going to respond to this one. Might have been you, might have been another.
"Railroading" does not require deception, but it's rare to have railroading that doesn't
include deception because players usually respond negatively to railroading that is 100% overt. But this brings up a very important point: there are several things that get
called railroading, but aren't.
Linearity isn't railroading. A player-driven story can still be quite linear if the players, totally unprompted, believe there's only one reasonable course of action, or if they agree that a linear story makes sense. For example, they go to a cave. Caves generally are cul de sacs, they don't go anywhere, you have to exit from (more or less) the same point you entered, or at least near to it. If the party goes into a cave they want to investigate, they're probably going to expect to come back out from the original entrance after having defeated the bad things inside. That can still be 100% purely player-driven without any railroading.
Likewise, running a module isn't railroading, if the GM is clear about what they're doing. Can't run a module and pretend it's a homebrew campaign, sure, but folks kind of have to understand that a module is going to entail
some restrictions of their choices in order to continue to make sense over time. Any player who doesn't accept this is either being foolish or disingenuous. Of course, any GM who acts like running a module gives them free rein to enforce one and only one action at every moment is also being either foolish or disingenuous, so it's not like the player is the only one who could go wrong here, but it's more likely to be a player error than a GM one of we are assuming at least a minimum effort at good faith.
More subtly, cause and effect/action and consequence aren't railroading, though a deceptive
appeal to them can be. That is, actions have consequences. That's something everyone needs to accept in order for a game to function. Avoiding the usual cliche assassination example, consider something like "actively supporting a pretender to an empty throne". (Remember, in this context, "pretender"
does not have a negative connotation; it's just the term for someone who lays claim to a title, without comment on the merits of their claim.) People will judge the party for supporting that candidate and not others. This will open some opportunities and close others. Now, a deceptive appeal to "consequences" or "cause and effect" is
most certainly a common tactic for trying to deflect player concerns about real railroading, visible or not, but the fact that someone can assert it as a guise to deflect accusations of railroading does not mean that all cause and effect/action and consequence situations are railroading.
Ham-fisted railroading, what one might call "naive" railroading, is usually just beneath the skin. It's rare for it to be done
so overtly that it can't be at least a little bit covered up (because such overt control is generally disliked)...but it's not impossible. Handing out pre-generared characters, for example, is often a prelude to railroading players, since the character, being GM-created, can be argued to never have motives the GM doesn't approve of. But
because this is well-known as a preliminary to pretty open railroading, few players are particularly eager to do this.
Illusionism is the word for railroading that is actively concealed, where the GM relies on repeated or continuous deception in order to make players
believe that they have freedom they don't and that the campaign is player-driven when it is not.