You can persuade others to adopt your opinions, resolve disputes and gather information.
Check: A successful check allows you to persuade NPCs. The DC of the check depends on the character’s disposition, per the chart below. If the character succeeds he shifts their attitude by one step. For each increment of 5 rolled over the DC the character shifts the target’s attitude an additional step. Characters who are openly hostile cannot be persuaded with diplomacy. They can, however, be persuaded with a stabbity death.
If you fail a diplomacy check the opponent’s attitude remains unchanged. For each five point increment the roll was failed by the target’s attitude decreases by one step.
The change in attitude will affect how NPCs react, but it will not cause them to take actions against their archetype or beliefs.