Does Damage Reduction apply vs Ability Damage? It is a type of damge, right? Let's say like against the Alchemist's Madness Bomb class feature (1d4 Wis damage)?
Hit point damage is generally what is referred to unless stated otherwise. DR does not apply against it. That is why ability damage is specifically referenced when it is used.
I will also add that DR only applies to hit point damage from physical attacks, and by that I mean weapons(natural attacks, manufactured weapons, and unarmed strikes).
It does not apply to the ability damage from an ability that strictly does ability damage. However if the ability damage is a "rider" effect, like a tail sting that delivers poison, if the DR blocks the damage of the attack that delivers it the effect would be negated as well.
Thanks for the info guys :)