Lying via telling the truth

[SOLDIER-1st]

I want to tell somebody the truth, but to do it in such a way so that they think I'm lying. Would that be Deception or Diplomacy?

[HammerJack]

So your actual goal is to convince them of the something that is not true (that this true statement is false)? That sounds like Deception.

[Deth Braedon]

I want them to believe something which I know is not true

me, I’d say “make a check against my DC” - then leave the GM to decide which DC it is (which is kinda the way everything rolls lately)

[Claxon]

I would maybe run this as a perform acting, lol.

You're telling the truth, but you're trying to do it in such a way that the person you're interacting with will be convinced it's not true.

[Kasoh]

You're deceiving someone. Its Deception.

[Captain Morgan]

Yeah, Deception applied to lies of omission and tricks this as well, IMO.

[Sean Cannon 565]

The action you are indicating is not specifically written, which means it is subject to GM interpretation. Here's a few ways this could be ruled by a gm, in my opinion:

1. Deception
Because you are attempting to deceive someone into believing information contrary to truth, you could use the rules "lie". While your words are not lies persay, what you are portraying (through intonation, feigned over-excitement, or whatever else you could use) is intended to create a lie. This would likely come at a penalty since it is Elaborate (as per Deception rules).

2. Sow Rumor Feat
Due to the complexity required to pull this off, and the desire to spread information in a specific way, this could technically require the "Sow Rumor" feat. What you are basically doing is disseminating interest, belief, etc over a particular bit of knowledge. That sounds like a rumor to me.

3. Perform (Oratory)
If the above two doesn't make sense, then this is likely the next best option. However, I don't think this perfectly encapsulates the situation. It could be argued that the previous mentioned notes of intonation and feigned over-excitement is akin to acting, and they wouldn't be wrong. Acting, especially in shows or while doing voice acting, involves immersing your character into the show by making it believable. And hundreds of people would try to convince you that Grey's Anatomy is a textbook example of how hospitals work despite its over dramatization. One could come to the conclusion that such deception falls under this category because of the dramatization likely involved.

[Deth Braedon]

Sean Cannon 565 wrote:

And hundreds of people would try to convince you that Grey's Anatomy is a textbook example of how hospitals work despite its over dramatization.

I literally laughed out loud at this comment.

Sure, there are lots of poorly informed people who will try to convince you of something they just know is true yet their alleged knowing has zero foundation in reality.
And one doesn’t have to look very far to find more examples than one could regale in a day.
But maybe that - zero foundation in reality - is exactly what’s needed here.