This research has examined reflective equilibrium as a method for normative political philosophy from the perspective of Aristotelian dialectic. John Rawls’s reflective equilibrium is dialectical in the sense that it refers to people’s common opinions or considered judgements as a starting point for enquiry to formulate the principles of justice. However, this method is criticised by Richard Hare and Stephen Stich in that people’s common opinions might be biased, and that these opinions cannot offer objective bases for morality because they might be coloured by individual differences, local cultures or genetic factors. The current research has addressed this epistemological problem in light of the recent argument on the dialectical conception of epistemic justification, and considered how this method offers a reliable basis for formulating ethical values. The analysis has described the process of ethical reasoning, particularly theoretical acceptance, thereby showing how the reflective equilibrium method works according to humans’ natural process of concept formation and how it contributes to creating a unified, systematic and objective scheme of ethical values. The current research has concluded that a dialectical approach contributes positively to the purpose of ethical theory, which is to clarify the ideas of ethical values and offer a conceptual framework for issuing ethical judgements.