A few people on the board question claims that morality should apply universally, I think a lot of their concerns might vanish if we had a more explicit presentation of the series of inductive conclusions that have led us to a universal moral framework.
We could show how we arrive at moral injunctions from our own
experiences, then show how the conclusions lack differentiating factors that make them only apply to us, thus allow us to transform them into universal moral principles.
1a. I do not like to experience violence.
1b. Don't subject me to violence if they want me to feel happy.
1c. Very few people feel happy when experiencing violence.
1d. Don't subject others to violence if you want them to feel happy.
2a. I do not arrive at logically justified conclusions when coerced to a particular conclusion.
2b. Don't coerce me to a particular conclusion if they want me to arrive at logical conclusions.
2c. No act of coercion can make a conclusion logically justified.
2d. Don't force others to particular conclusions if you want them to reach logical conclusions.
Using this approach we start with morality as a set of things
people should do in order to meet your personal preferences, then we
notice if the resulting injunctions contain no reference to anything
unique about you, i.e. contain no reference to a narrow context, lacking such a narrowing factor we can apply the injunctions to a wider context of all people,
all times, all places.
We will come up against the barrier that some people may actually like violence or some people may arrive at logical
conclusions when forced into doing so, etc. We can use facts of general
human nature from biology, psychology, pediatrics, to show the
anomalousness of these people and that their odd natures shouldn't
prevent us from a general morality, as general as biology / psychology / pediatrics allows.
Due to the is-ought gap we cannot remove the goals from the
injuctions. We can say "Don't force others to particular conclusions if you want them to reach logical conclusions" but not
"Don't force others to particular conclusions".
We could then set about categorising the goals: wanting
people to feel happy, not wanting people to feel happy, wanting people
to come to logical conclusions, etc. Perhaps we'd arrive at only two
categories 1: Wanting to live according to human nature and of reality,
2: Wanting to live against human nature or of reality.
If we get to this point a person would have only one way to deny our moral code: they want to live against reality or human nature.