Sorry to bother you guys. I wanted to ask you in my DnD game, we fought some goblins. They attacked us first. We killed most of them; my character gave the rest a chance to surrender and said he may let them go. He questioned the goblins I rolled an insight check, my character perceived as if they enjoy attacking people a little. He then decided to kill them would be safer, my cleric friend disagreed and we fought. My DM said my character did an evil act. Would you agree? His reasoning was that a bigger goblin forced them to. Sorry if this is a dumb question.
Both. It depends on who, what,when, where, how and the perception of the characters and Game master. Now I'm just a country Kobold lawyer but it seems like it would be an issue with procedural process combined with player inexperience hashing these things out at the tavern where the adventures always begin. Did the cleric have to roll a perception check? Did the cleric check what the gods position on preventing future harm? It's "Batman syndrome". Batman has decided that killing is the line at which he becomes evil. I have thought about this sooooooo much!! Ok here we go. Batman has a hand in the creation of nearly all of his enemies so he shares responsibility for future harm. Sometimes the situations don't give Batman the knowledge that the vat of acid didn't kill Jack Napier but merely elevated him to joker status. I.e. Level up. But many situations afforded an opportunity to end a spree of violence permanently which Batman refuses based on his arbitrary decision that killing is the line that cannot, must not be crossed. But the joker keeps escaping from Arkham asylum, going on a new spree of violence and murder and all the nasty things that make him so "evil" according to Batman and the general societal consensus that killing is bad Mmkay? But Batman actually takes full responsibility for every harm committed after Batman chose not to end it permanently. So NOT killing Joker is more evil, especially when it happens over and over and Batman refuses to end it, that responsibility is compounded exponentially until Batman becomes the most evil of all when multiplied by all the villains he won't kill times all the second and third chances he had to do so. If your character perceives that this won't be the end of mayhem and that somewhere some poor thing is going to be dragged into the warrens to an unimaginable fate, stopping that is most good. But to the cleric whose interpretation of their gods rules is more like the wild west where if all parties had guns and were shooting it's a fair fight if it started by choices those parties made based on masculinity or whatever, it was "Killing" not "Murder" and was therefore legal. But if in the case one guy shoots the gun out of the others hand and that person no longer has equal ability to fight, to kill this "unarmed" outlaw is murder. If it was a fight for dominance then they can both walk away if they both aren't liable for disturbing the peace or some such local law. If the disarmed is a bad guy here to pillage then he must be handed over to the Marshall. Your character sought to avoid "Batman syndrome" while your cleric companion sought to hand them over to the Marshall. Basically your Game master failed his perception check to realize the differing principles of the party. Because "Batman syndrome" is as far as I know, a concept of my own intellect I can understand why and how this happened. P.S. I will relinquish claim if someone proves that the term was coined before 1996 when I came to the realization that Batman is a coward and narcissist of epic proportions,seeking only to play the game not win.
So. Something important to understand about Dungeons and Dragons is that, unlike in our reality, Gods actually exist and have real and tangible consequences and agency in the world in which they live.
In our world, we have a problem for a theological model of morality which is called the Euthyphro dilemma. Identifying Goodness with the will of the Gods introduces a problem, which is to ask whether the Gods do what they do because it is good, or whether what they do is good by definition because it is what they do.
In the Dungeons and Dragons multiverse, it's easy. Alignment exists within a pantheon. Some Gods are Good, and doing what they like is doing a good thing. Some Gods are Evil, and doing what they like is an evil thing. Good and evil are perceived in certain ways by creatures and people in that world and as such they align themselves to certain domains which are overseen by those Gods, deciding everything within their domain.
So, if you want to plead your case as being a Good action, you have to ask yourself - which God are you pleading to?