Ethics
Ethics asks which actions are right, what makes them so, and what kind of claim a moral claim is in the first place. The beginner tier fixes the vocabulary: the difference between describing and evaluating, what a reason is, what a moral theory owes you, and what metaethics is asking that first-order ethics is not. The intermediate tier works through the standing families of theory and the metaethical landscape they sit in, including motivation and reasons, both of which are ordinary undergraduate material rather than specialist territory. The advanced tier is where the live disputes are: the embedding problem, the semantics of moral terms, the source of normative authority, holism about reasons, and the impossibility results in population ethics.
Beginner
No prior exposure assumed. Every term is defined where it first appears.
Intermediate
Undergraduate level. Formal machinery, standard results, and the objections that stuck.
Advanced
Graduate level. Metatheory, technical variants, and disputes that are still open.