| Chris Kenney |
When it comes to alignment, I see them as more forces than things that define individual behavior. Thus, most people in the game world (and most PCs) are Neutral. A few "mortal" races (Dragons, Drow in Golarion, ) have an innate alignment, as do all undead (Evil) and outsiders (by type). These are innate alignments, and no matter what you do, if you have one of these alignment traits you are ALWAYS treated as that alignment.
It is also possible to acquire an alignment. Paladins count as Lawful Good, and clerics are always the alignment of their diety. Finally, at character level 5+, if you lack an alignment you can take a feat that gives you an alignment of your choice (Good, Evil, Lawful, or Chaotic) and also lets you treat any of your attacks as being of that alignment for overcoming DR (Clerics and Paladins can also take the feat to gain this ability for their granted alignment.)
If you manage to acquire contradictory alignments (The infamous drow ranger, for instance) you are treated as whichever alignment is worse.