what is meant by hence a theory which leads to an examination of the psychological and historical origin of people's moral opinions should be more useful than a theory which postulates moral truths enunciated by self-evident intuitions that are unchangeable

Answer and Explanation:

This means that a theory which leads to imposing moral standards universally without regard to people's historical and psychological differences are based off of subjectivism and lack any form of thorough investigation (normative science). This is self explanatory in the question where it says " ... postulates moral truths enunciated by self-evident intuitions that are unchangeable". Moral standards such as this are mostly based on traditions that are subjective and are not given to transparency. This is opposed to when questions may be asked and investigations come into play as to why a particular moral opinion is taken enabling a society appreciate or understand a moral stance based on it's historical, cultural or psychological origins.