Paladin and rogue in the same group - what's allowed and what's not?

[Mnemnosyne]

No, it doesn't. Killing an [EVIL] outsider is a non-evil act. All the time. Every time.

I agree. I was just clarifying your statement. After all if you stab a tiefling in the back of the head while he's eating his dinner because he pinged on detect evil, and for no other reason, you've just committed murder, an evil act. If you do the same thing to a succubus because your true-seeing revealed it to you, you get a free pass because it had the [evil] descriptor tag. You might have a problem with some by-standers if you can't prove she was a demon though.

If you walked into A'kin the Arcanaloth's shop and murdered him as a paladin, you could try to use that argument. But in any game I run, you'd be making that argument as a fighter without bonus feats, not as a paladin, because you would have fallen for murdering someone who has not demonstrably harmed anyone. The same applies to killing a random succubus just because you happened to see what she is.

However, stealing from people is always harming them, whether it's evil or not. The paladin's code explicitly states that the paladin must punish those who harm or threaten innocents. As long as the person being stolen from cannot be demonstrably shown to be non-innocent, they are by default, innocents. Therefore the paladin is obligated to punish anyone stealing from them. Not because stealing is evil, but because theft unquestionably harms the victim of the theft by depriving them of the product of their work, whether that be money, food, or some other thing.

Even ignoring the paladin's code, it's not too reasonable that most good characters would be inclined to ignore someone indiscriminately stealing. Stealing from a merchant can cause them serious harm - if you steal an expensive magical item from them, this may cause their business serious harm. Perhaps even make them go bankrupt, if enough of their capital was invested in it. Would any good character be ok with making innocent people lose large quantities of money, possibly lose their business? It might be justifiable if this was the only way to stop some greater problem, but in the case of just random indiscriminate theft, it's certainly not justified.