I would prefer an action-by-action assessment.
Save your life = good.
Sacrifice you later in a ceremony to a demon Lord = evil.
Evil might then become as arduous an alignment as Good, and maybe even more difficult to follow, since everyday life is based on a lot of goodwill towards others :)
The first problem I see with this is that sentient beings are extremely skilled at explaining away their destructive actions as being for the best or for the greater good. Thus, if you listen to the perpetrator, no one will ever commit an evil act, and thus no one will ever be evil.
Since the...
I am afraid that your argument holds no real weight. We just have to consider an opposite situation.
You are dying from thirst. A guy comes to you and gives you something to drink, basically saving your life.
But maybe he is an evil cleric just wanting to use you in one of his evil plans. By...
My basic philosophy is that no player should ever do something that ruins the fun of another player. Lethal aggression against another PC definitely breaks the code.
What about a mirror ?
If a mirror lies within the range of your darkvision, can you see on it the reflection of things further away ? What about the reflection of things which fall out of your darkvision range when you add (distance from said thing to the mirror)+(distance from the mirror to...