Final answer:
The claim that each historical period is morally superior to the previous is false. Historical relativism suggests morality varies with historical context, and Normative Ethical Relativism argues against universal moral principles, claiming morality is culture-specific.
Step-by-step explanation:
The statement that each successive historical period is morally superior to previous historical periods is false. This idea conflates historical relativism with a progressive view of history that assumes moral improvement over time, which is not a tenet of historical relativism. Historical relativism actually suggests that morality is understood in the context of each historical period and no one period is necessarily morally superior to another.
Normative Ethical Relativism posits that moral standards are determined by cultures, and there are no universal moral truths that apply to all societies at all times. As such, this theory can be challenged when considering moral reforms instigated by minority groups within a society, as these reforms would imply a deviation from the majority's moral standards, which is supposedly the correct view in normative ethical relativism.
Different societies may develop different moral perspectives, based on interactions with individuals and societal institutions, leading to a variety of rules, mores, laws, and ethical ideas, hence the varied forms of moral relativism. However, accepting moral relativism can lead to difficulties in overcoming moral disagreements due to its nature as an anti-realist position that denies objective moral justifications.