>>43292432The DnD system actually explicitly states that the "greater good" mindset is not "good".
Ex: A paladin comes across a plague-ridden village, where the villagers are all dying with no cure. The paladin, being lawful good, HAS to try and help them. However, the plague is highly contagious and spreads quickly, so the logical (albeit cold-hearted) decision would be to purge it, ala Arthas. A paladin who does this would fall, as even though it was for the greater good, he knowingly committed an evil act. If you're looking to play a paladin who slowly falls or loses faith, this is one of the better ways to go about it. "Good" characters in DnD cannot commit evil acts, even if they are the "correct" decision. Otherwise, they're evil or at best neutral.