Normative ethics
Normative ethics (cf.
metaethics) is the branch of the
philosophical study of
ethics concerned with classifying actions as right and wrong without
bias, as opposed to
descriptive ethics.
Descriptive ethics deal with what the population believes to be right and wrong, while normative ethics deal with what the population should believe to be right and wrong.
"Killing one's parents is wrong," is a normative ethical claim. Given that parricide is wrong, normative ethics has no further interest: why it is wrong is someone else's concern.