For James Rachels, our opinions about what is moral are value-laden and subjective. He discusses the concept of moral subjectivity, building on and challenging the legacy of previous philosophers, notably Hume’s. Rachel qualifies Hume’s theory that sentiment is the source of moral judgment as a form of simple subjectivism (SS). Simple subjectivism refers to the false assumption, so goes the argument, that moral opinions are detached from our personal stances. Rachel has issues with SS because it assumes that we do not commit mistakes and it makes a simplistic analysis of what constitutes morality. SS is appealing to people, nevertheless, because as Rachel points out it gives the perception that everybody agrees on what morality is.
Another milder form of subjectivism is emotivism. Emotivism refers to the differentiation between facts and moral language. An ethical statement does not necessarily refer to a fact. An ethical statement is not a factual statement by default. This makes emotivism less pretentious about the positivist nature of morality. Rachel is yet against emotivism because it does not account for Reason. Emotivism is centered around emotions. Emotivists target influencing attitude and not really providing the reason for why is this or that act is immoral. Emotivism brings no answer to what constitutes morality.