@DChristopher Sorry, i missed the 'not'
You may have another reason to try to rule out determinism, but i think pre-determinedness is a reason not to have this discussion. Watching the road still prevents you from crashing your car, regardless of determinism. If a person were not to watch the road because he thought it was pre-determined anyway, the likelyhood of crashing his car would be higher. (likelyhood in a frequentists probability interpretation, if you wish) (btw i dont think the universe is deterministic.)

I will try make another iteration of the ethics-axiom idea, i will call 'want' 'feel' now, since it is closer to what i mean. Note that i also mean how they feel "averaged over time". (which has problem of how to average then)
Axiom: Goal is to make all creatures together feel as good as possible, with the importance of each creature weighed.
Now to try to atleast list problems about this:
-What is a creature?
-How is the importance of a creature weighed?
-How do you know how a creature feels.
Honestly, i do not know how to deal with these questions. Wether something is a creature is perhaps not so important, if it is not a creature, its importance is simply "zero". So what is the importance of a creature? Could try something like how complicatedly it behaves, or its nervous system. In practice though i am afraid, i just stick to what i associate with what i know about the creature, same for what the creature is feeling. Maybe a good approach is to give the creature the freedom to do what it wants, and assume that it will appease itself. (this is not passive, some one without food does not have the freedom to eat, giving him food is non-passive.)
-What is feeling (good)?
Well, i do not know how to deal with this one either. :/ It seems similar to the what is the meaning of life question.

I guess i will for now go pragmatist, and much like DChristopher, encapsulate these four question into judging case by case what creatures might be thinking and what "value" they have. In that sense, my axiom adds little, but it does rule out hate by the way. (unless perhaps it makes you feel damn good.)

Edit: Note that the axiom is more a goal to set, not a axiom at all.