Non-lethal weapon damage - does a magic bonus add?

Question

Is there any place in the manual where the following statement is proven or disproven?

You can't add your weapon's magical bonus if you want to deal nonlethal damage with it.

(My answer would be "no, it's not specified you don't" but AFAIK it's not specified you do either. I need sources, or at least several things tied together by logic. Working logic.)

Answer 1

The rules don't say either way literally, I don't think, but they do say so by inference:

1. A magic weapon's enhancement bonuses apply to attack and damage rolls.
2. Dealing nonlethal damage with a weapon still requires attack and damage rolls.
3. Therefore, enhancement bonuses apply to nonlethal attacks with a magic weapon.

In terms of the game world's internal reasoning, it can go however the GM decides because magic has no real-world analog. One can hardly say a magic sword is realistic or not!

Answer 2

There is nothing that I have seen or could find that would imply that you don't get your weapon's magical bonus to causing non-lethal attacks.

Switching lethality already has a penalty that is called out explicitly in the form of a -4 to attack rolls. If there were other costs or penalties with other core effects (such as magic items) it would stand to reason it would be listed in the section marked for just that:

Nonlethal Damage with a Weapon that Deals Lethal Damage

You can use a melee weapon that deals lethal damage to deal nonlethal damage instead, but you take a -4 penalty on your attack roll.

Lethal Damage with a Weapon that Deals Nonlethal Damage

You can use a weapon that deals nonlethal damage, including an unarmed strike, to deal lethal damage instead, but you take a -4 penalty on your attack roll.

From a logical standpoint if a weapon is easier to use or works better for magical reasons, using it in a way that's slightly more difficult should still have it perform better than an otherwise identical mundane weapon wielded similarly.