How does failing a Sense Motive check against a Bluff affect your character's perception of the world?

Question

There doesn't seem to be a concrete explanation for what happens to your character if you fail a Sense Motive check against a Bluff. I want to know the limits of failing a Sense Motive check, as well as the effect it has on your character and their mindset.

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The wording of 'Sense Motive' is pretty straightforward:

A successful check lets you avoid being bluffed (see the Bluff skill). You can also use this skill to determine when “something is up” (that is, something odd is going on) or to assess someone’s trustworthiness. (Core Rules, p. 104)

The issue I'm having is that failing a sense motive check isn't outlined in the skill itself. The closest I can find is in the 'Bluff' check description:

Bluff is an opposed skill check against your opponent’s Sense Motive skill. If you use Bluff to fool someone, with a successful check you convince your opponent that what you are saying is true. (Core Rules, p. 90)

Due to the way the game I'm in is structured, most of the people that we meet are either hostile to us, or at the very least don't want us to succeed. Furthermore, most of the people we interact with have absurdly high bluff checks, to the point that I can't recall any of us successfully detecting a lie with 'sense motive' (despite us being lied to nearly constantly).

For instance, we recently had an encounter with a devil who we were sure knew the whereabouts of a MacGuffin. We also knew that this devil had a history of tricking adventurers by giving them bad directions that sent them into ambushes. So, we talked to this devil, and sure enough he gave us directions to the MacGuffin. The interaction then went like this:

Devil - "Oh yes, I know where that is. You just need to take the Winding Road, and make a left at the big gnarled tree. No one uses that path, it'll get you there safe and sound"

Fighter - "I don't really believe this guy one bit. I'm rolling sense motive to see if he's lying to us. I rolled a 29"

GM - "(rolls) You think he's telling the truth"

Naturally, he wasn't telling the truth, and we ended up getting ambushed.

The problem is that by deciding to roll a Sense Motive check, we basically forced ourselves to accept the results of the check instead of our own intuition. Since we know we have a good chance of failing the checks no matter how well we roll, it seems advantageous to us to make as few sense motive checks as possible. That way, at least we can have some chance of recognizing when we're being lied to. In the example above, if we simply didn't try to roll a Sense Motive, all of us would have been almost 100% sure the devil was sending us into an ambush, and we would have planned to go another way. However, since we tried to determine if it was a lie, we ended up failing the check and then believing that it was the truth, which put us in a much worse position than if we just hadn't attempted to determine if it was a lie in the first place.

The Hunch option of Sense Motive seems like it tries to address situations similar to this:

This use of the skill involves making a gut assessment of the social situation. You can get the feeling from another’s behavior that something is wrong, such as when you’re talking to an impostor. Alternatively, you can get the feeling that someone is trustworthy. (Core Rules, p. 104)

Unfortunately in our game, I know that everyone we meet is not 'trustworthy', and that 'something is up' at all times. Knowing the devil isn't trustworthy doesn't give me anything useful; I know he's untrustworthy, he's a devil. However, sometimes you need to work with untrustworthy people, and in those times it's important to be able to try to suss out what they're being truthful about, and what they're lying about. With Sense Motive the way it's written, it seems like it's better to not roll unless you're almost 100% sure you'll succeed, or else you're going to be convinced that the lie is actually the truth, instead of just not being sure if you're being lied to or not.

Is there anything official that deals with the limits of believing a lie?

In my example, does failing a sense motive check mean you truly believe the devil is being honest, without a doubt? Does the failed check assuage any feelings of uncertainty you had about the situation? What should characters do when they're pretty sure they're being lied to, and they're also pretty sure they'll never be able to pass their sense motive checks?

Answer 1

Your question doesn't have a RAW answer

The rules are actually silent on that matter. Social skills are given more freedom in terms of GM fiat than certain other pieces of rules.

Social skills shouldn't work against PCs in most cases

It removes player agency

What differs a tabletop role playing game, or a computer RPG from a book is player agency. The GM gives the players a plot, but it's the players who decide what their characters do, how they actually react. That's why they even came to the game, bothered to learn the rules, build a character, etc.

What you saw is called railroading

Many GMs can be tempted to take player agency away in one form or another to make players follow their pre-written plot: this is called railroading. Preparing an adventure is very hard, especially if one is not very experienced as a GM, or if the players are very creative, but it's a huge trap to force players onto the rails carefully placed in the game because at the end of the day they will notice it and be frustrated. This answer by @mxyzplk shows that some railroading is actually inevitable, but too much railroading (what you see) is probably what a good GM should try to avoid.

Social mind-control

Social skills actually work almost identically to mind-control spells. There is a check: if you fail it, you have to do what someone says. You are afraid of someone if it's Intimidation and have to work with them as if they were your friend, you actually treat them as a friend if it's Diplomacy, and you believe their nonsense if it's Bluff. Even if what your GM said was not intimidating at all and actually made you laugh, even if your gut feeling tells you that the NPC isn't friendly, and is actually lying right now.

OK, but... why do they even exist?

To be used against NPCs.

Your GM knows that you are trying to fool a villain. To decide if the villain knows that too, the GM makes you roll Bluff opposed by the villain's Sense Motive. You want to make friends with someone, you role-play the dialogue, your GM wants to check if the way you talked matched this someone's personality, your GM rolls. By the way, Diplomacy's DCs are trivial even for some quite low-leveled characters.

Using those rolls saves time, allowing you to role-play only a short part of the conversation, allows your character to be capable of stuff you are not capable of (say, making friends easily), and removes GM's headache of thinking within the limits of the said NPC's knowledge, which the GM would probably need if there were no rolls.

And, you know, NPCs don't care when their plans fail because of a die roll, while it often makes players angry.

This saves even more time if NPCs are rolling their social skills against each other and the GM doesn't know how they want to resolve the conflict.

OK, the game actually gives many enemies real mind-control! Shouldn't I use it in place of social skills then?

Indeed, it's an interesting mechanic, but it's like a spice. If you season your food with it just a bit like once a month, its taste is interesting. If you add a fistful of it in every meal you eat, it quickly becomes rotten, boring, not something you perceive as fun.

Same goes for mind-control spells. The first time you throw them in, it can be something cool if you know how to inject it properly. The tenth time it will either be a routine defensive response from your players (e.g. Protection from Evil) or will just frustrate your players very much.

Even if mind-control is rolled against players, save DCs should be reasonable

By throwing a monster at you who has e.g. +38 to Bluff, your GM practically made you fail any Sense Motive checks against the said NPC. It's the same as saying "You will do as this guy (played by me) says). Now, imagine if the Devil's bonus was only +9, while your Sense Motive is +15. Sounds more fair, aye? There is a chance for you to win, a chance to lose... Should probably give you a slight adrenaline boost in real life.

There are exceptions

1. Sense Motive by NPCs. When an NPC rolls it, they don't force you into acting as they say. Quite the opposite: they avoid being forced, so it's OK.
2. Intimidate to Demoralize Opponent. Many forget that this way of using Intimidate even exists, but it actually does. It's not mind-control, it's just a debuff, so it's also totally OK. The same goes for using Bluff to Convey a secret message, Feint in combat, and similar stuff that doesn't totally remove your right to act.
3. Asking for it. Your Fighter actively asked for Bluff to be rolled against him. It might or might not mean that they now totally believe that what an NPC said is true. It might or might not mean that other characters also think so (all the GMs I have seen would at least also give other characters a chance to roll). But your Fighter wanted to use an instrument that didn't work, and saw consequences.

Have a Session 0 to talk about it

In short, you don't like what your GM is doing. Next time you gather to play, bring up this issue. If other players also find this unfun, perhaps your GM will change their attitude to the subject. Perhaps, you will understand that you are the only one frustrated. Perhaps, this will mean that your group needs a new GM, or that you need a new group. All those possible endings are actually OK: many people here on RPG.SE would agree that no gaming is better than bad gaming, and, in fact, in the modern world it is usually quite easy to find other RPG players.

At least you have something to clarify, e.g. how your GM actually wants social skills to work, when they are to be rolled, etc.

Same Page Tool might be very helpful if you want to invest some more effort in bringing your expectations closer to each other.

Answer 2

Assess your target's trustworthiness

By asking your DM in the way that you did, you effectively forced him to have the devil bluff against you and has an opposed roll (Bluff vs Sense Motive). If you instead have a hunch that the devil is untrustworthy, and want to roll to have your character's gut feeling of the situation that's an unopposed roll against a straight DC (Sense Motive vs Hunch DC, usually 20)Core Rulebook p104.

The results are subtle but very different:

In your situation you asked directly to be able to tell if someone is lying, since the target is lying and is obviously trying to do so the DM has to say okay, I guess he's bluffing then. Make opposed rolls, and you fail because the devil is good at lying. Since he's now using a skill, if you fail the check that means he succeeds in his skill, so you believe his lies. Though if I was your DM I would have given some sort of penalty to the devil due to the previous knowledge you had about him (did you ask for this?), but maybe yours did and the devil just rolled a 45 so it didn't matter.

If instead you have a hunch that a person is untrustworthy and do a sense motive to assess their trustworthiness in this particular interaction (which generally takes a full minute) then you could find out that no you shouldn't trust that guy, but you really wouldn't have any information as to whether or not he was lying in this particular instance. Your 29 in sense motive would've passed here. Additionally if I were the DM, I'd probably reduce the DC of this check from 20 down to a more reasonable level due to the circumstances regarding the reputation that this devil has already. It might give you a 5-10 point reduction in the DC due to the circumstances. Additionally a failed check here just means that you didn't come to a conclusion, not that you come to the wrong one.

Also note that your sense motive hunch doesn't have to address whether the subject is generally trustworthy or not, it can be limited in scope to address whether in this instance he is acting in a trustworthy way. You could prolong the conversation, grilling him about the details of his supposed lie as a part of this process of sensing his motives. "So it was a right at the oak tree?"

Answer 3

To answer main part of the question:

Is there anything official that deals with the limits of believing a lie?

The bluff rules says:

Bluff checks are modified depending upon the believability of the lie. (...) Note that some lies are so improbable that it is impossible to convince anyone that they are true (subject to GM discretion).

You know it is a devil. You know it's pure evil in physical form. Any sentence claiming something is innocent and safe may very well count as unbelievable, or at least have a heavy penalty to bluff roll.

Also, believing what he says to be true does not have to make you take a course of action he suggests. Think like "he seems to tell the truth, but he told us nobody uses this path, so maybe there is a reason he simply don't know?"

And there are rules about suggesting a course of action.

You can use Bluff and Diplomacy together to make a request of a creature, without it even realizing you have made the request.

Player Characters are immune to Diplomacy, so they are immune to suggesting a course of action, too. You do not have to take that route devil suggests, period. At least, not if you are using rules from that particular book.

Source: Giant Hunter’s Handbook

Answer 4

You need to understand that Diplomancy is a powerful weapon, and take active measures against it

So, a 29 is a very bad Sense Motive check to be expecting going into a meeting with a powerful enemy liar. Any Diplomancer worth their salt is definitely going to be subject to glibness when it matters, and that alone is a +20 bonus. A 29 isn't terrible-- it'll keep the devil from repeatedly telling you impossible things and forcing you to believe them, probably, because that would take at least a 49 and that's a pretty decent target for a low-level bluff-based BBEG, but it's definitely not going to keep your whole party safe from a dude who's whole deal is messing you up with social checks. No, for that you need a better plan.

So, first of all, you should never let someone you know has a massive Bluff score talk to the party. Just don't listen, don't give them space to talk, carry thunderstones if you have to: do whatever's necessary to keep them from getting to make a Bluff check. In this case that means when you show up your party should all be deaf and probably subject to telepathic censure or similar. You should then beat the devil unconscious, tie it to a chair, cast dominate monster or some other form of magical compulsion to force it to be truthful or to rip the knowledge directly from its mind and/or corpse, and only then allow yourselves or better yet a trusted specialist or expendible guinea pig to handle the information in question.

Alternatively, you can try to have a meeting with the devil. You should not be rolling sense motive during that meeting, and the devil should not be rolling Bluff. Either of you, of course, could break the rules at any time and bust out your social skills, in the same way that either of you could pull out a plasma rifle and unload a full clip of ammunition into the other. You don't do that, though, because people who sneak attack the other side during a parley don't live very long and can't expect others to honor their parleys in the future. Besides, you can have someone not attend the meeting so they can solve the problems if it goes badly, and you can probably have your sense motive dude bust out the weapons if the devil busts out a Bluff check.

Social skills in Pathfinder (and D&D 3.5 to a lesser extent) are not so much abstractions of how real in-character social interactions should go as weapons that affect the targets' minds rather than their bodies. Bluff is mind control, just like dominate monster or modify memory or-- most similarly-- 3.5's mindrape. Your party should regard it as such, and be extremely cautious around creatures who are capable of using it effectively. Just because PCs get carte blanche immunity to Diplomacy checks does not make them similarly immune to Bluff checks, and they should not underestimate the danger enemy Diplomancers pose.

If this bothers you, you may wish to suggest to your DM that mind control not be included in your Pathfinder game, including extreme uses of the Bluff, Diplomacy, and Intimidate skills. This is a fairly common house rule across 3.x games and in my experience it has worked fine though it does significantly change how the game is played and also limits the total dominance of magic-users over their mundane kin.

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But what are the technical limits of Bluff? Am I actually worse off calling for a Sense Motive roll?

There are a couple of limits to what you can forcibly change in a character via Bluff. Specifically, bluff allows you to cause a target to believe any specific thing:

with a successful check you convince your opponent that what you are saying is true

Unlike many other skills, there is a maximum to how hard the GM is allowed to make a Bluff check for you:

Note that some lies are so improbable that it is impossible to convince anyone that they are true (subject to GM discretion).

and from the table:

Circumstances: The lie is impossible Modifier: –20

So you can know that if you roll 20 points higher than a target's Sense Motive roll you can generally make them believe anything you want. If your bluff total is 39 higher than a creature's Sense Motive total, you can generally make them believe whatever you want all the time with no chance of failure. I say generally here because there may be other circumstantial or feature-based modifiers to this DC (most notably the modifiers found in Ultimate Intrigue), but the point stands that with enough Bluff you can convince anyone of anything. "These are not the droids you are looking for", for example.

You can also use Bluff to replicate telepathy, making a trivial DC 20 check to force a creature that shares a language with you to receive a message and using that check's Bluff result to prevent anyone else from being able to discern your true meaning without a superior Sense Motive result. This lets you make your Bluff "you believe this now" statements secretly, among other things.

You can also use Bluff with Diplomacy to convince people that your Diplomacy use isn't actually happening and the 'requests' you are making of them were their own idea in the first place.

You can use Bluff to convince people as a group not to pay attention to you, though not usually the inverse, to roll initiative in duels, and for many many other things you purchase for the skill with feats or traits.

You cannot use Bluff to oppose active uses of the Sense Motive skill the same way that skill is used to oppose active Bluff checks, except via the feat Veiled Contempt and even then you may only add twice your Bluff ranks to the DC. That said, a player calling for a Sense Motive check can learn from it only that the target is generally untrustworthy, not that any specific statement was a lie, and the 'hunch' so gained does not free them from the damage done via being lied to. Bluff is always used v.s. Sense Motive, but that's a separate check from the one that is used when a player calls for a roll.

You cannot use Bluff to make a request of a character nor to suggest a course of action, except as a modification/enhancement to your Diplomacy roll. Diplomacy does not work on PCs, so you can't have your PC's attitude altered that way, nor can the devil force you to comply with requests it makes that way. You can only use Bluff to force PCs to believe false information, not determine what they do with that information. The Intrigue rules go into this in some detail:

Bluff Doesn’t Define a Response: Even the most successful lie told using Bluff doesn’t determine the course of action the deceived person takes—it just primes the target with misinformation.

Unfortunately, the intrigue rules do also suffer from several contradictions with the CRB, particularly with regards to the limits of the Bluff skill, and so depending on which source your group regards as more authoritative your play will go differently there. None of the rules in Intrigue prevent Bluff from working as it otherwise would categorically, they just let the GM forbid the player from succeeding at some kinds of checks by saying that impossible should be changed to 'almost impossible' or that alternatively success could sometimes just means the NPC believes that the PC believes what they are saying, rather than believing the proposition put forth, etc. Essentially it provides a lot of ways you could change the Bluff rules as a GM if you wanted to to make the players less able to use them without disrupting the ability of NPCs to use them if you don't like that PCs can convince NPCs of crazy stuff.

So, in conclusion, as regards technical stuff, the devil should have rolled Bluff as soon as he was lying to you if he wanted that lie to have the force of a Bluff check behind it. If he did, it would automatically be against the Sense Motive check of his target, and he would need a separate Bluff check for each member of your party and the conversation would take at least several rounds instead of a couple of free actions. It is totally reasonable, however, that your party would, if it stuck around for those rounds, become convinced that the MacGuffin was located in the pit of deadly death and that not swan diving into said pit would result in your being cursed with seven years bad luck.

Your later, active, sense motive check would be entirely separate from that. It would tell you, barring abilities the Devil had to the contrary, that the devil is not a trustworthy fellow and also something is up. It would not tell you those things you had been convinced of were false, and it would not tell you that the devil was the source of those ideas if the Devil had caused you to believe those things subtlely. You, then, would decide what your characters do, which could include being pretty sure the stuff they believe is wrong, killing the devil, and running away to try and process their cognitive dissonance. It could not, however, include no longer believing the things they have been convinced of-- even if they suspect they might be wrong-- without "new information that allows them to realize the truth of the matter" (again from the intrigue rules).

In short, you are not worse off calling for a sense motive roll except that that means you have to be around a Bluff user for a full minute of time. Your sense motive roll is not opposed by the target's bluff check, but it doesn't let you know if any particular statement is a lie-- that's your passive Sense Motive roll you make in reaction to being Bluffed at.

As you note, if you already know that a target is untrustworthy and using Bluff, then Sense Motive is only of use for you as a meagre defense against their persuasive abilities. Instead, you shouldn't be talking with them unless you can guarantee that they are not going to use social skills. In your description of your game this seems unlikely and so a violent solution where the information is forcibly obtained is probably expected.