Final answer:
The justification for the leader irrelevance argument in the Theory of Normative Ethical Relativism can be supported by historical evidence, cultural norms, and ethical principles.
Step-by-step explanation:
The justification for the leader irrelevance argument in the Theory of Normative Ethical Relativism can be supported by multiple factors. One factor is the presence of historical evidence. Historical evidence shows that moral standards and beliefs have changed over time, indicating that they are not fixed or universal. Another factor is the recognition of cultural norms. Different cultures have different ethical standards and practices, further supporting the idea that morality is relative. Lastly, the existence of ethical principles can challenge the leader irrelevance argument. While moral perspectives may vary, there are certain ethical principles that can be considered universal, such as the right to life and the wrongness of killing.