So the player's roll actually does determine if the receptacle exists, not if the PC sees the receptacle. Or rather, not simply if the PC sees it...the roll determines both the presence and the viewing of it.
I don't think using the words "exist" and "presence" in that way is very helpful. It encourages category mistakes.
Whether or not the vessel exists, and is present in the room, depends on the actions of beings in the shared fiction (eg did a house servant take a chamber pot into the room? did someone bring a jug of water into the room? etc).
Stepping out of the ingame perspective into the real world, of course no vessel exists - nor does any of the rest of the fiction - it is all made up and imaginary. And the content of the shared fiction can be determined in all sorts of ways. One way is via player checks - in particular, if the player succeeds on a check that establishes that his PC can see a vessel in the bedroom then that state of affairs becomes part of the shared fiction. Which means that the presence of a vessel in the bedroom also becomes a part of the shared fiction.
An analogue in classic D&D - which [MENTION=22779]Hussar[/MENTION] might remember from past discussions - is the paladin's power to call for a warhorse. The player's activation of that power makes it true, in the shared fiction, (i) that the paladin has some sort of dream/vision of the location of the warhorse, and therefore (ii) that said warhorse is present in said location. But the existence of the warhorse is not a result of the paladin calling for it - the warhorse was foaled, grew up, etc, long before the paladin called for it.
Note in both cases that the player action declaration is only one way of introducing the given element into the shared fiction. For instance, as I explained upthread, a failed check to notice the vessel might also introduce the vessel as a part of the shared fiction - but broken rather than ready-to-hand for blood collection. In the case of the paladin's warhorse, the GM may have mentioned some foaling horses at some earlier time in the campaign, and now use the occasion of the paladin calling for a warhorse to reintroduce one of those foals into the game.
So setting this DC with about a 1% chance of failure is more meaningful than simply saying "yup, it's there"? I mean, clearly the player is up to something by asking....so Justin saying yes would seem to save some time and no the really impact the drama.
When you say the player is up to something . . . you seem to imply that the GM may not know what.
In the approach that my table uses, the GM always knows what it is that "the player is up to". Action declaration is both intent and task. Knowing both is key to framing the check, to understanding how it fits into the unfolding action, and - if the check fails - to narrating failure. (Eg it is only because the GM knows that the player wants the vessel to collect blood that it would be appropriate to narrate, on a failure, that the familiar is eating the blood.)
As to why to set a DC even if it's low? Multiple reasons: it's part of the ritual of play; it highlights the significance, to the unfolding events, of this particular moment of action - Tru-leigh wants a vessel to collect the blood for his master, but can he see one that he might use? And it opens up the possibility of failure and hence the dramatic pacing of rise and fall, even for something easy. If the PCs only even fail on hard things, that changes the tone of the drama. It makes the feel of the game less gritty. And this particular game aims for a gritty feel. (This is a difference from, say, 4e.)
In your failed check/fail forward example, I don't see how it's the check that really does all that much. In this example, you've said the the result of the roll is pretty much a given. And I don't think that you mentioned anything about the degrees of failure or success based on how far the roll was from the DC...so all the alternatives (the broken chamber pot, etc.) are all still the product of DM judgment.
I don't quite follow.
The result of the roll is either success - in which case the PC gets what the player wanted for him (namely, he can see a vessel in which he can try and collect the blood) - or failure - in which case some sort of failure has to be narrated. I gave a couple of examples of what those might be.
I'm not sure how degrees of success/failure factor into this - of the systems I run regularly, the only one that routinely cares about degrees of success/failure is Marvel Heroic RP. But yes, adjudicating the consequences of failure is a GM judgement call. I didn't think that was in doubt. But I'm not sure what further conclusion you're drawing from that.
Nowhere have I posted anything critical of GM judgement calls in general. In the OP I gave an example of a judgement call - setting a DC - that I don't see as railroading. In subsequent posts in this thread I've given further examples.
I just don't see the required connection between the dead end point and DM judgment.
I don't understand this. You asked, "Does a failed check really open so many alternative paths that a DM saying "there is no chamber pot" does not?" and "Do you feel that from the player's point of view there is a significant difference between a failed check compared to the DM simply saying no?"
I explained why I prefer "fail forward" to "dead end" failure (eg "Just as you notice the jar on the table, it is knocked over and smashes" to "No, there's no vessel"). "Fail forward" relies on GM judgement (to narrate some consequence of failure that pushes the action onward) in a way that "dead end" narration does not (hence my incredulity at [MENTION=37579]Jester David[/MENTION]'s suggestion that I could get the play experience I've talked about in this thread by playing without a GM). So the only "required connection" is that "dead end" narration doesn't require GM judgement, whereas "fail forward" does.
As far as the GM substituting a judgement to "say no" for a check, there is no particular connection between that and "dead end" failure - as I posted upthread, GM might by way of fiat describe the jar being smashed, or the familiar licking up the blood, without calling for a check and hence without allowing the possibility of the player getting what he wants for his PC. But, as I said in the OP, I would regard such an exercise of judgement as railroading - it is the GM shaping the outcomes (ie the highly salient and significant events within the shared fiction) in order to fit some preconception of what should happen. So it's not something that I would do.
This is where I question your choice to label it as a railroad. So far, I am not seeing a meaningful difference.
To be clear - are you saying you don't see any difference between a GM narrating failure by fiat, and a GM setting a DC and then the player checking and failing?
