Is all morality subjective?

If you were asked whether it is wrong to torture an innocent child, your immediate reaction would likely be one of absolute, non-negotiable horror. Yet, if morality is merely a byproduct of human evolution or cultural conditioning, that horror is no more objective than a dislike of broccoli. This is the central tension of moral philosophy: we live our lives as if moral facts are as real as gravity, yet we struggle to find them in the physical world. To answer whether all morality is subjective, we must distinguish between *where our moral beliefs come from* and *whether those beliefs refer to objective truths*. ## The Case for Moral Realism Many philosophers argue that morality is objective, a view known as [Moral Realism](https://plato.stanford.edu/entries/moral-realism/). Realists argue that certain moral claims are true regardless of what any individual or culture believes. Just as the earth was round before humans discovered it, certain actions are wrong regardless of our opinions. The prominent philosopher G.E. Moore argued in his landmark work, *Principia Ethica*, that "good" is a simple, indefinable property that we perceive through moral intuition. Realists point out that when we debate moral issues, such as human rights or justice, we are not merely expressing personal tastes. We are behaving as if there is a correct answer to be found. If morality were entirely subjective, a statement like "slavery is wrong" would merely mean "I dislike slavery," making genuine moral disagreement impossible. ## The Case for Moral Anti-Realism Conversely, defenders of [Moral Anti-Realism](https://plato.stanford.edu/entries/moral-anti-realism/) argue that morality is fundamentally subjective. A major proponent of this view was the Scottish Enlightenment philosopher David Hume, who famously argued in *A Treatise of Human Nature* that we cannot derive an "ought" from an "is." > "Take any action allowed to be vicious: Wilful murder, for instance. Examine it in all lights, and see if you can find that matter of fact, or real existence, which you call vice... The vice entirely escapes you, as long as you consider the object. You never can find it, till you turn your reflection into your own breast, and find a sentiment of disapprobation, which arises in you, towards this action." In the twentieth century, J.L. Mackie championed "Error Theory" in his book *Ethics: Inventing Right and Wrong*. Mackie argued that while our moral language *claims* to be objective, all such claims are actually false because objective moral values simply do not exist in the universe. Ultimately, while our *perceptions* of morality are undoubtedly shaped by subjective factors like culture and biology, the question of whether a fundamental moral reality exists remains one of the most vital debates in philosophy. ## Follow-up questions 1. If evolutionary biology can fully explain why we feel certain actions are wrong, does that completely undermine the argument for objective moral truths? 2. How can moral realists explain the vast and persistent disagreement about moral issues across different cultures and historical eras? 3. If we accept that morality is entirely subjective, on what grounds can we legitimately judge or interfere with the practices of other cultures?

If you dropped a wolf, an ant, and an extraterrestrial octopoid onto a planet with scarce resources, they would all eventually develop a rule prohibiting unprovoked internal murder. This insight suggests that morality may not be a fragile human invention, but rather a universal law of social physics—as inevitable as the evolution of eyes on an illuminated planet. The view that morality is an inevitable byproduct of physical reality relies on the concept of **convergent evolution**. Just as dolphins and ichthyosaurs independently evolved hydrodynamic bodies to navigate fluid dynamics, social organisms must evolve cooperative behavioral constraints to survive the game-theoretic realities of a physical universe. ## The Game Theory of Physical Reality In *The Evolution of Cooperation*, political scientist Robert Axelrod demonstrated through computer tournaments that in iterated "Prisoner’s Dilemma" scenarios, strategies that display reciprocal altruism consistently outperform purely selfish strategies. Because our universe is characterized by thermodynamic scarcity, finite space, and mutual vulnerability, living entities face identical mathematical realities. An organism that cannot form stable coalitions will systematically lose resources to groups that do. > "The strategy of 'tit-for-tat'—starting with cooperation and then simply doing whatever the other player did on the previous move—achieved the highest average score... Cooperation can evolve even in a world of egoists." > — Robert Axelrod, [The Evolution of Cooperation](https://www.basicbooks.com/titles/robert-axelrod/the-evolution-of-cooperation/9780465005642/) Therefore, functional moral constraints—such as prohibitions against random violence, expectations of reciprocity, and sanctions against free-riders—are not arbitrary cultural traits. They are optimal solutions to structural problems imposed by the laws of physics and mathematics. ## Law of Nature vs. Objective Moral Fact Does the inevitability of moral codes make them *objective*? The answer hinges on how we define objectivity in philosophy, creating a productive tension between biology and metaphysics. 1. **Functional Objectivity (Constructivism):** If a set of rules is the *only* stable solution for social persistence, those rules are objectively valid relative to the goal of survival. Thinker Michael Ruse calls this [Evolutionary Ethics](https://plato.stanford.edu/entries/ethics-evolutionary/). Humanity experiences these rules as objective "commandments" because natural selection wired our brains to perceive them that way. 2. **The Metaethical Counterargument:** Critics like philosopher Sharon Street argue in her influential paper on "Darwinian Dilemmas" that evolutionary inevitability still fails to establish true moral realism. If our moral codes are merely selected for survival, they track *evolutionary fitness*, not independent, immutable "moral facts." If the environmental constraints of our universe were radically altered—say, if offspring were produced effortlessly and endlessly—the mathematical optimum would shift, and a completely different "moral code" would become inevitable. Ultimately, if intelligent life naturally converges on cooperation, moral codes are indeed a "given" feature of the cosmos. Morality may not exist written into the fabric of space-time alongside gravity, but it exists as an unavoidable structural property of any universe where complex, social matter tries to endure.

Consider the *fine-tuning problem* in cosmology: if the strong nuclear force were just two percent stronger, diprotons would be stable, stars would burn out in seconds, and chemistry would collapse. If we push this cosmological logic one step further, we arrive at a startling conclusion: physical constants do not merely predetermine the existence of carbon atoms and galaxies; they predetermine the eventual emergence of justice. If the basic physical laws of a universe make complexity and sociality inevitable, then morality is not an accidental biological side-effect. It is a structural property hardcoded into the initial conditions of the cosmos. ## The Fine-Tuned Universe and Emergent Realism Cosmologists like Luke Barnes and John Barrow have long documented how life depends on extremely narrow ranges for fundamental constants—the gravitational constant, the proton-to-electron mass ratio, and the cosmological constant. However, physical constants do more than assemble stars; they dictate the **nomological structure** (the system of natural laws) that governs how matter interacts over deep time. If a universe possesses physical laws that permit: 1. **Thermodynamic dissipation networks** (allowing localized entropy reduction, or life), 2. **Resource scarcity** (governed by the conservation of energy), and 3. **Information inheritance with variation** (darwinian evolution), then that universe possesses a deterministic evolutionary trajectory toward social complexity. Philosopher Philip Kitcher terms this structural progression in [The Ethical Project](https://www.hup.harvard.edu/books/9780674061446) as a functional transformation. Under this view, moral practices are not cosmic accidents, but rather functional inventions driven by deep evolutionary pressures that naturally arise whenever intelligent agents interact under physical constraints. > "Ethical practice arose as a human response to the difficulties of living in social groups... Ethics is a human invention, but it is an invention that was bound to be made." > — Philip Kitcher, *The Ethical Project* If Kitcher's functional necessity is correct, then in any universe sharing our nomological framework, the physics guarantees the chemistry, the chemistry guarantees the biology, the biology guarantees the game theory, and the game theory guarantees the morality. ## Strong Nomological Determinism: Moral Inevitability To push past mere biological convergence, we can look at philosopher [Thomas Nagel](https://nyu.edu/)'s controversial work *Mind and Cosmos*. Nagel argues that standard materialist evolutionary theory is incomplete because it treats the emergence of mind, value, and reason as an uncaused cosmic fluke. Instead, Nagel proposes a form of natural teleology. > "The existence of conscious minds and their access to the evidential sources of knowledge about the world... is a fundamental feature of the world, not an accidental byproduct of physical processes." > — Thomas Nagel, [Mind and Cosmos](https://global.oup.com/academic/product/mind-and-cosmos-9780199919758) If we extend Nagel's teleology to nomologically equivalent universes—universes that share our exact set of physical laws and constants—morality becomes a cosmic property. In this view, moral truth is not an abstract, non-physical object floating in a Platonic realm, nor is it a casual quirk of human culture. It is an **inevitable emergent phase transition** of matter. Just as water unexpectedly crystallizes into ice when temperatures drop, matter under the influence of standard physical constants inevitably crystallizes into cooperative, rule-bound moral agents when complexity reaches a critical threshold. Morality is thus built into the initial conditions of the Big Bang. Any universe born with our physical laws is pregnant with the imperative to cooperate.