And this means I can do a Shrodringer's Gun with the locations: the dungeon just happens to be where I need it to be for the players to find it. They've missed a few plot hooks, and I've had to provide them with more obvious ones, but since they are more inclined to talk to NPCs than the first group I took through the module I've had to improv a lot.
When I feel like railroading, I always think of Shrodringer's Gun and that usually kills the temptation. Ask yourself "How important is it that X happens?"
Do the players have to talk to the king to get the quest? Does the King have to be in a certain place in order to give the players the quest? As long as you keep your object firmly in mind, you won't railroad...much.
- emphasis added
I honestly can't tell what stance the poster is making, but he says clearly and well what I find seems to be the position a lot of other posters are hedging around.
Namely, he seems to be saying that so long as you keep the illusion of player choice up, you aren't actually on the railroad.
But look at that last sentence, "As long as you keep your object firmly in mind, you won't railroad...".
That to me shows the inherent contridiction in such a stance. The whole concept of "railroading" is that the DM has some destination (and often some journey) so fimly in mind that he doesn't allow deviation from it. Nothing so gaurantees that you'll railroad the players as having some destination firmly in mind.
The most powerful tool a DM has for railroading his players is there lack of knowledge about the game universe and his ability to manipulate what they can't see to force them back onto the DM's desired path. Some DMs are better than hiding the rails than others, but its all railroading and no proper discussion of railroading can be undertaken until you realize that. Otherwise, you'll be busy trying to say that your railroading isn't railroading because its 'good' and railroading is inherently bad, so what you are doing to insure the PC's do exactly what you want them to do can't be railroading.
Railroading refers to a broad variaty of techniques for effectively limiting player choice so that the story proceeds according to the DM's wishes. Sometimes these ways are subtle, sometimes they are intrusive, sometimes they are arguably justifiable. In fact, the majority of players accept railroading as a necessary feature of the game in some circumstances. But all the different techniques share in common that they limit player choice and turn players into observers with limited ability to effect the current or future situations.
Let me suggest some definitions:
"Linear": A game where one event follows logical from the previous and moves toward a predictable destination without side treks.
"Theme Park": A game that is sparcely detailed except for a few areas intended to be attractions. The attractions are usually connected by some sort of short railroad that whisks the players between attractions. Players have an expectation of empowerment and freedom only within the attractions.
"Adventure Path": A linear theme park. Often associated with published modules because a complex adventure can be orchestrated on a comparitively few pages and requiring comparitively low reliance on DM experience.
"Sandbox": A game, or a portion of a game, which is evenly detailed over a wide area and carries an assumption of a large amount of player freedom and empowerment. Generally seen as the opposite of 'linear'. Often associated with home brews because of the large amount of work involved to successfully set up the sandbox, although some published worlds (FR, HARN, and campaigns based loosely in the 'real world') are sufficiently detailed to support some sort of sandboxing.
"Rowboat": A degenerate sandbox which involves scant or nonexistant details and poor player empowerment. Often associated with 'winging it', especially by GMs with limited experience running other types of games and thus without a ready toolbox of plots, places, and characters to draw from.
"Railroad": A degenerate Adventure Path where not only you can't get off the train, you can't choose not to get on it, or an Adventure Path that consists solely of train and no attractions. Often associated with homebrew adventure paths where the GM has fallen to much in love with his own imagined story and outcomes, but sometimes seen in published adventures (DL if played without a DM experienced in sandboxing, some 2e AD&D especially for the FR, published VtM modules, certain CoC adventures, etc.)
"Playset": A campaign that liberally switches between adventure paths and sandboxes to try to capture the best of both, frex a sandbox that contains numerous themeparks or an adventure path which passes through several very broad attractions with multiple sidetreks.