Is all morality subjective?

If two people look at the night sky and one sees a flat dome while the other sees infinite space, their disagreement does not prove that the universe lacks a true shape. It merely proves that one of them, or perhaps both, has an incomplete perspective. Moral realists face a formidable challenge: if objective moral facts exist, why do cultures across time disagree so violently on issues like slavery, gender roles, and warfare? To defend their position, realists do not need to claim that moral truths are obvious. Instead, they argue that moral disagreement is not a symptom of subjectivity, but rather a consequence of cognitive limitations, non-moral disagreements, and developmental progress. ## The Illusion of Disagreement: Shared Values, Different Facts One of the most powerful realist counterarguments is that historical and cultural disagreements are rarely about fundamental values. Instead, they are disagreements about *factual, non-moral beliefs*. The contemporary philosopher [Michele Moody-Adams](https://en.wikipedia.org/wiki/Michele_Moody-Adams), in her book *Our Kind of People: Talk and Talk and Talk*, argues that many apparent moral disputes disappear once we isolate the empirical beliefs of the participants. Consider a historical culture that practiced witch trials. To a modern observer, executing an innocent person for witchcraft is a grave moral atrocity. However, the historical actors and the modern observers actually share the same moral principle: *it is wrong to allow dangerous murderers to go free*. The disagreement is not moral; it is empirical. The historical culture believed, as a matter of physical fact, that witches existed and caused real harm. Once the scientific facts are corrected, the moral evaluation aligns. ## Moral Blindness and Cognitive Distortion Just as physical blindness does not disprove the existence of light, "moral blindness" does not disprove the existence of moral facts. Realists argue that self-interest, prejudice, and social conditioning can distort our moral perception. In his paper [“Moral Disagreement”](https://philpapers.org/rec/BRUMD), philosopher David Brink argues that deep-seated biases prevent individuals from apprehending objective moral truths. A society relying on slave labor has a massive economic incentive to rationalize the practice. This is not a lack of objective moral truth; it is a case of motivated irrationality. This perspective positions moral discovery as akin to scientific discovery. For centuries, humanity was mistaken about the nature of disease, attributing it to bad air or divine wrath. We did not conclude that biology is subjective; we recognized that discovering objective truth is difficult. > "The fact of ethical disagreement no more shows that there are no objective moral facts than scientific disagreement shows that there are no objective physical facts." > — David Brink, *Moral Realism and the Foundations of Ethics* ## The Argument from Moral Progress If morality were purely subjective, the concept of "moral progress" would be incoherent. We could say that our moral views have *changed*, but not that they have *improved*. To explain historical disagreement, realists point to a clear trajectory of moral convergence over time. The philosopher Peter Singer famously described this as the ["expanding circle"](https://opil.ouplaw.org/view/10.1093/law:epil/9780199231690/law-9780199231690-e835) of moral empathy. Historically, human empathy was restricted to the tribe. Over millennia, through rational debate and shared experience, that circle has expanded to encompass other races, nations, genders, and increasingly, non-human animals. This persistent, directional movement suggests that humanity is slowly mapping an existing objective moral landscape, correcting its past errors as it gains clearer vision.