I studied philosophy at university and am currently a philosophy teacher at a high school. So, obviously I think philosophy is rad. However, if teaching to a bunch of kids who didn't get to choose my course has taught me anything, it is that philosophy isn't for everyone. That said, practical philosophy is usually (wrongly) considered to be the most interesting and approachable kind. So even if you aren't into philosophy, maybe give this a read?
Anyway, let's overthink make-believe games from the perspective of moral and ethical philosophy (yes, there is a difference. Just stick around until the end if you're interested in it).
Three dimensions of RPG ethics
I think ethics and morality come into TTRPGs in three ways.
First, there are game mechanics/world building aspects that tie into morality. Alignment is the most famous of these, though any gamification of morality and any worlds with some objective good and evil will fall into this category, which I'll call "in-universe morality".
Second, there are ethical dilemmas and moral calls to action placed in the game by whomever is running it to entice the players. The first is there to force them to make difficult decisions as their characters, the second as a hook. I'll call these "gameable ethics and morality"
Finally, there is what I would like to call "the ethics of running games". This basically comes down to running a game you can stand behind, concerning what you put into your world, how you depict these things, but also how you interact with your players and what player actions you tolerate.
This discussion mostly revolves around alignment, however I think it applies to any world or system that makes a claim to objective goodness or evilness. I am not going to make any statements about whether or not using in-universe morality is good or bad. Personally, I dislike it, but that isn't the point. What I do want to do, is make clear the underlying assumptions of in-universe morality are, that I feel people often take for granted.
- First, all in-universe morality assumes that there are objective labels that can at least in some cases be applied unequivocally in your game. E.g. if you have 'good' as alignment, you are implying that you are able to apply that label to certain things or acts within your world. Which means you invariably take the high ground in worlds like that.
- Second, in-universe morality does not assume you believe such labels can be applied in the real world. You might very well believe there is no absolute goodness in the real world. However, this is a thin line. By saying 'this is what goodness is in this fictional world' you are often communicating 'this is what I think goodness is in general' even if you don't hold that belief.
- Third, there is the implication that as the GM you to some extent force your beliefs about alignment on the players. You might not mean to do this, but you are doing it. Even if you are open to suggestions from players about whether or not something is more or less good, your initial response will be to describe the act or thing in question as 'good' and as GM that carries weight.
You might be able to live with these assumptions; universities seem to agree with you, as they keep teaching morality and pay good money for people researching the subject. But, just know that there are compelling arguments against objective, universal morality. And I personally find them more compelling than arguments I've heard in favour of it.
Gameable ethics and morality
A moral call to action can be a pretty good way to get your players to do stuff. In fact, I think a lot of traditional hooks that aren't motivated by rewarding the player with money or stuff are moral imperatives: 'Save the village from destruction', 'Rescue the child from the monster', 'Help out the oppressed elderly person', or anything of the sort will usually get players moving.
Moral dilemmas are an equally useful tool. The crux of a lot of the 'game' aspect of RPGs is making meaningful choices. From asking your players to choose between something they seem to care about and in-game advantages, to choosing between one thing they want and something else they also want, these dilemmas are nice examples of meaningful choices.
As tools, moral imperatives and moral dilemmas can be used to different ends. One end towards which these tools can be used is the smuggling in of objective labels of good and evil, without explicitly using in universe morality. If you as the GM feel like there is a 'right' choice in your moral imperatives or your moral dilemma's and make the entire world react as if there is only one correct choice, the world basically still has an implied in-universe morality. Which, depending on your beliefs, is something you might want to lean into, or something you might want to avoid.
However, you can just put this stuff in the game and let your players decide what they or their characters think is important. You just don't punish them for deciding not to respond to a moral imperative or for choosing what you believe to be the wrong thing in a moral dilemma. Rather than appealing to some universal morality, you instead depend on the individual ethics of your players and their PCs. It doesn't matter whether or not it is 'the right thing to do' to prevent the death of an innocent person, at the cost of blowing the cover of the rebellion who is trying to end the tyranny of the monarch. What matters is whether or not your players feel it is the right thing to do.
Now, by no means is this supposed to advocate for having there be zero consequences for the choices of your players. That would make these tools less about meaningful choice, which was exactly the benefit they had. However, frame it as if people in this world have opinions about your players' actions. The people of this town hate your PCs for letting the innocent bystander die when they find out you could have stopped them; they are not part of the rebellion and only care about struggling to survive this harsh world. You can make your players feel bad about their choices, without moralizing.
The ethics of running a game
No matter your stance on in-universe morality (both on covertly using gameable morality to that end or overtly by having Good and Evil be part of your universe or system) as the GM you have an ethical responsibility towards your players. The reason for this is quite simple: It is implied in most systems that you sign off on anything happening in the world, meaning you are complicit in your players' actions. When a player says 'I want to lure the deadly monster towards us for no other reason than because I think it would be funny', you saying 'sure, go ahead' makes you complicit in the potential death of the party, because you signed off on it.
Not only are you partially responsible for what your players do in your games, you are also responsible for what your players encounter, how the world reacts to their actions and how you interact with your players both inside of and outside of the game. Sure, players have some of these responsibilities as well, but the nature of most TTRPGs is such that there is a power imbalance, an implied hierarchy, and as such you as the GM have more responsibility than your players. Simply the fact that, if you don't show your players can't play at all, while if one of them doesn't show it is up for debate whether or not the group will still play, proves this point.
TTRPGs are inherently DIY, so there is no excusing your behaviour by saying that you are just 'running what is in the module', or 'playing the system as it is written'. Anything you don't want to include, you can just leave out or even just reskin. Note, that the choice to take no stance on a subject is also a stance. Because if you think that your players should be able to do whatever they want, you value something (freedom to do whatever you want) over something else (e.g. a safe play environment). The idea that abstaining is being neutral or apolitical is my personal number one frustrations with a lot of contemporary discourse.
Distinguishing ethics from morality
Now for those who stuck around mostly to find out what distinguishes ethics from morality.
As Michel Foucault defines morality it is a "code", i.e. a set of rules that applies to a moral community. For Peter Singer, the moral community includes anything that can suffer, and the code is 'do what decreases the total amount of suffering in the world'. For nazi's, the moral community includes only the 'chosen race', with codes that are supposed to bring about and protect this 'chosen race's' supposed supremacy and purity.
Ethics, by the definition of Foucault in the same work, are a way in which the subject relates to itself. Morality implies an ethics; to be able to do what would decrease the total amount of suffering in the world you need to be a certain kind of person. Trying to be that person, and all that that entails, is ethics. The nice thing about looking at ethics this way, is that it doesn't require morality to function. Depending on your values, you will try to act a certain way. You don't need universal codes for that.
Personally I dislike morality. Not because I think there is no reprehensible behaviour, I have strong opinions about lots of things (including teaching morality at university). Neither do I dislike it because I think the freedom to have differing opinions is more important; I am not a tolerant person, some behaviour truly disgusts me. It is mainly because morality can easily function as the basis for oppression. If I make a claim of knowing for a fact what is right and what is wrong, I might be completely blind to my own biases and wrongfully condemn entire cultures on the basis of deeming my own cultural background to be 'the default'.
What I want to leave you with then, is not a moral code that you should uphold as a GM. Nothing like 'make sure the table is a welcoming place', or 'address problems as they arise'. As advice, those statements might be very useful, but their applicability is limited. If you are dealing with untolerable behaviour, you might not want to welcome those acting that way at your table. If you feel unsafe, you might not be able to address a problem as it arises.
So instead, consider what you can live with. Both in how you run your game, in what you put in it, and in how you deal with your players. I'm not suggesting you strive for perfection; this is just a hobby for most of us. However, keep in mind that you do have an ethical responsibility and keep in mind that doing nothing is also taking a position. Just ask yourself: am I ok with how I am running my games?