A lot of people seem to think that ethics is subjective. This does make some sense; what each of us feels is morally right in any given situation can often differ, and differences in what people believe is right have driven countless conflicts throughout the course of human history, so it’s really no wonder that there might seem to be no definitive answer. Even philosophers, who have spent quite a large sum of time pondering the issue, aren’t particularly united behind one specific answer (although this really shouldn’t be a surprise, academia seems to primarily make progress through what is essentially very formalized arguing), with some even arriving at positions which accept that peoples’ differing beliefs of what is good and right are entirely culturally relative and incomparable*. With that, the subjectivity of ethics seems to be both an intuitive and widely corroborated characteristic. However, there’s a reason I haven’t claimed that ethics is subjective in the title of this post.
*I need to find the specific paper I'm thinking of as an example of this, I'm pretty sure it's a Nussbaum article about the incommensurable nature of "good" across cultures and how this can be approached through aristotelian ethics, future self please put it here when you find it.
Take, for example, the following argument:
I'm sitting in a room typing this right now. If I wanted to leave this room and move into the hallway outside, I would be objectively more likely to succeed if I were to walk through the room's doorway rather than trying to walk through one of the walls. Regardless of how proficient I believe myself to be in the art of walking through walls, no amount of will or belief on my part is going to change the reality that I can't walk through walls. Therefore, if I wished to achieve a desired goal of making it out of this room, I should walk through the doorway.