Ethical intuitionism posits that moral truths are known through intuition, suggesting that certain moral principles are self-evident and do not require empirical evidence or rational argumentation to be understood as true. This perspective emphasizes the immediate apprehension of moral values and duties, arguing that our moral intuitions are a reliable source of ethical knowledge.
Moral realism is the philosophical view that there are objective moral facts and values that exist independently of human beliefs or perceptions. It posits that moral statements can be true or false based on these objective standards, similar to factual claims about the physical world.
Self-evidence refers to propositions or truths that are immediately known and accepted without need for further proof or reasoning, often considered foundational in philosophical and logical discourse. These propositions are typically characterized by their clarity, distinctness, and necessity, making them immune to doubt or contradiction.
The Open Question Argument, proposed by G.E. Moore, challenges the idea that moral properties can be reduced to natural properties by arguing that for any proposed naturalistic definition of 'good', it remains an open question whether that definition truly captures what 'good' means. This suggests that moral terms are indefinable in naturalistic terms, implying a form of moral non-naturalism or ethical intuitionism.