The other day Jokkl asked a question on this blog about pen & paper RPGs: "why should I roll some dice when I want to bribe someone or something like that?". I know that was meant as rhetorical question, but I'd like to answer it anyway.
Nearly all of us have been "roleplaying" when we were kids, we just didn't call it that. We played cops & robbers, or cowboys & indians, or superheroes, or something similar. And when kids play like that, inevitably the same situation pops up: One kid says "Peng, peng, you're dead!", while the other kid claims his sheriff star caught the bullet or the bullet missed him. So most pen & paper roleplaying systems have a way to resolve this situation with dice. Dice generate random numbers, rules tell us what the probability is of the level 2 fighter with the longsword +1 hitting the level 3 orc, and the combat situation is resolved.
But of course pen & paper roleplaying games aren't just about combat. In fact a pen & paper game has a much larger scope of different possible events than a computer game, because pretty much everything is possible as long as the players can imagine it. So there is *real* dialogue instead of clicking on one of three choices. The DM plays all the NPCs, and the players play their characters.
In these roleplaying dialogues sometimes the players want to achieve something specific, for example find out an information, or persuade somebody to do something. It is perfectly possible to play through let's say a bribe situation just by using dialogue. But at some point the DM has to make a decision on whether the NPC accepts the bribe or not. And suddenly we are back to "peng, peng, you're dead". The player is almost certainly sure that he roleplayed the bribe so brilliantly that the NPC should accept it. The DM might not be of the same opinion. And the DM might even want to have different degrees of difficulty in bribes: The general is harder to bribe than the soldier, for example. Using rules, probabilities, and dice rolls again helps to resolve the situation. That doesn't mean that all dialogue is replaced by dice rolls, but if there is a question of whether something succeeds or not, dice are an option.
Rolling dice in such situation has two more advantages: It helps staying in character, and it balances the attention each player gets better. In a completely free-form roleplaying situation without any dice rolls, you inevitably get some of the more extrovert players hogging all of the limelight. Add social skills with dice to the system, and every player ends up with skills for different situations, and gets to shine when that situation comes up. What is tested is the skill of the character, not the skill of the player. So just like you don't have to be very strong in real life to play a fighter, you don't have to be very intelligent and charismatic in real life to play a diplomat.
And then of course you can mix and match. For example you let the players play out the bribe situation with dialogue, and then let them roll the dice at the end. You can even give bonuses to the roll for good roleplaying. Or even drop the need to roll the dice if the outcome appears obvious for everybody. Dice are only needed to resolve a conflict. And they are good at it, being perceived as impartial. Sometimes they are just a perfect tool to keep everybody happy, and that is what playing these games is all about.