What epistemological challenge does moral realism face?

The epistemological challenge that moral realism faces centers on how we can know objective moral truths if they exist. Moral realism posits that moral facts exist independently of human opinion or belief, similar to how physical facts exist. However, unlike physical facts which can be observed and tested through empirical methods, it is difficult to explain how we can gain knowledge of moral facts. This difficulty is often referred to as the 'epistemological problem' for moral realism. The core question is: If moral properties like 'goodness' or 'rightness' are real and objective, how do we detect them or come to know them? Our usual ways of knowing things (observation, experimentation, logical deduction) don't seem to apply directly to moral facts. For example, we can observe someone helping another person, but how do we objectively 'see' that the act is morally good? This lack of a clear and agreed-upon method for accessing moral knowledge raises doubts about the existence of objective moral facts themselves. Critics argue that the absence of a reliable epistemology undermines the realist claim that moral truths are mind-independent and objectively real.