Can you roll social skill-checks against other players?

Question

This is the situation: In a group of four people, they've stumbled upon a magically locked tower. They discover a balcony, and three of the PC's want to enter through there. The Lawfully Good paladin however, thinks this is bad and thinks they should leave it alone. One PC decides to distract the paladin while the other two explore the tower.
Of course, eventually the paladin starts suspecting something, and starts asking questions. In this situation, should the distracting player make a bluff check, followed by the paladin rolling a Sense Motive as if they were interacting with a NPC, or should they RP it out? Are there rules about this in the books, or should this be discussed with the DM?

I want the answer to apply to these skills:

• Bluff
• Intimidate
• Sense Motive

Answer 1

... the difficulty in proving a negative notwithstanding

RAW: yes, roll, usually

RAW has no problem with PCs using skills "on" other PCs (there's nothing in the Bluff Skill Description preventing it, for instance). Similarly, PCs would use Hide/Move Silent vs. Spot/Listen to hide from each other, just like PC/NPC interactions.

Note, however that Diplomacy specifically mentions that it's only usable on NPCs:

You can change the attitudes of others (nonplayer characters) with a successful Diplomacy check; see the Influencing NPC Attitudes sidebar, below, for basic DCs.

Don't be a Dick

I've had one game break up entirely (and a couple of others have rough patches) when one PC tried to lie to the rest of the party, but I've also had great fun in games where PCs were lying to each other; the latter were funny and good-spirited, while the former were potentially plot-relevant. YMMV†.

Thus, from personal experience, I would recommend role-playing the interaction, and erring on the side of not lying (at least, not about important things). Then roll, keeping in mind the Bluff/Sense Motive modifiers (and any situational modifiers that might be appropriate, if one character is a known fibber).

† Your Mileage May Vary

Answer 2

Yes, PCs can use skills against each other, even in an adversarial manner.

However...

From personal experience you must allow the players to override the results of the dice or the game will quickly break down.

So in the situation above I would handle the outcome of Bluff/Sense Motive checks by informing the players of what their characters feel and then allowing them to choose how to roleplay the situation.

So in this case the dice affect the characters emotions but the players determine how the characters react. It's a relatively fine distinction but avoids any feeling of the player's being forced to act in a certain way.

In addition you might want the character attempting to Bluff the Paladin to make some sort of roll or provide an in character justification for what is veering close to an 'evil' act, but that depends a lot on your campaign style and setting.