Philosophy · Contested
Moral Intuition as Evidence in Ethics
Many moral philosophers treat strong, widely shared moral intuitions, such as that gratuitous cruelty is wrong, as a legitimate starting point for ethical theorizing, a methodology that is itself philosophically contested regarding its reliability and justificatory force.
The evidence explained
In normative ethics, many philosophers, following a method associated with John Rawls's account of 'reflective equilibrium' in A Theory of Justice (1971), treat considered moral intuitions, judgments about particular cases or general principles that seem obviously true on reflection, as legitimate data points that ethical theories must accommodate or explain, similar to how observations function as data for scientific theories, adjusting either the intuitions or the theory until they cohere.
Proponents of intuition-based moral epistemology, including ethical intuitionists such as W. D. Ross and, more recently, Michael Huemer in Ethical Intuitionism (2005), argue that certain moral truths, such as that gratuitous cruelty is wrong or that promises generally ought to be kept, are self-evident or knowable through rational reflection in a manner structurally similar to how certain basic logical or mathematical truths are grasped, without needing to be derived from some more basic non-moral premise.
Critics raise serious objections. Moral intuitions vary across cultures, historical periods, and individuals in ways that are difficult to fully explain if they track objective moral facts, a concern developed by moral skeptics and error theorists such as J. L. Mackie in Ethics: Inventing Right and Wrong (1977), who argued that the seeming objectivity of moral intuitions is better explained as a projection of human attitudes than as genuine perception of mind-independent moral facts. Evolutionary debunking arguments, developed by philosophers such as Sharon Street, further argue that moral intuitions can be substantially explained as products of evolutionary pressures favoring reproductive fitness rather than tracking independent moral truth, which would undermine treating them as reliable evidence unless one can show evolutionary pressures reliably track moral truth as well as fitness.
Defenders respond that evolutionary debunking arguments prove too much, since evolutionary pressures also shaped human perceptual and cognitive faculties generally, including those used in mathematics and science, without this being taken to universally undermine perceptual or mathematical knowledge, and that the existence of some disputed or culturally variable intuitions does not undermine confidence in widely and cross-culturally shared core intuitions, such as prohibitions on wholly gratuitous cruelty, which some argue require a different kind of explanation than culturally contingent norms.
The status of moral intuition as evidence in ethics remains a live and unresolved methodological dispute, with reflective-equilibrium and intuitionist methods enjoying wide but not universal use among practicing moral philosophers, and moral skeptics, error theorists, and evolutionary debunkers offering serious ongoing challenges to treating intuitions as reliable guides to objective moral truth, assuming objective moral truth exists at all, itself a further contested metaethical question.
What it does show
- • Widely shared, cross-cultural moral intuitions (such as prohibitions on gratuitous cruelty) are treated by many philosophers as legitimate starting data for ethical theorizing.
- • The reflective equilibrium method provides a structured, non-arbitrary way of weighing intuitions against theoretical principles.
- • Convergence of intuitions across highly diverse cultures and traditions on certain core moral judgments is itself a notable, if contested, datum.
What it does not show
- • It does not establish moral realism (that objective moral facts exist) as opposed to competing metaethical positions such as error theory or expressivism.
- • Evolutionary debunking arguments raise a serious, unresolved challenge to treating intuitions as tracking mind-independent moral truth.
- • Significant intuitional variation across cultures and individuals on many specific moral questions complicates any simple appeal to intuition as decisive evidence.
Primary sources and literature
- John Rawls, A Theory of Justice (1971)Foundational statement of reflective equilibrium methodology.
- W. D. Ross, The Right and the Good (1930)Classic statement of ethical intuitionism and prima facie duties.
- Michael Huemer, Ethical Intuitionism (2005)Contemporary defense of intuitionist moral epistemology.
- J. L. Mackie, Ethics: Inventing Right and Wrong (1977)Classic error-theoretic critique of objective moral facts and intuition.
- Sharon Street, 'A Darwinian Dilemma for Realist Theories of Value,' Philosophical Studies 127 (2006)Influential evolutionary debunking argument against moral realism.
Where scholars disagree
Moral philosophers remain divided over whether intuitions constitute genuine evidence of objective moral facts, are better explained by evolutionary or cultural forces without tracking independent truth, or should be understood within an anti-realist or expressivist metaethical framework altogether.
For further study
Primary and secondary sources on both sides of this question. Reading the strongest opposing case is part of the work, not a concession.
The Blackwell Companion to Natural Theology — William Lane Craig and J. P. Moreland (eds.)
The reference volume: long, technical chapters defending each major theistic argument, with the best statements of the cosmological, fine-tuning, moral, and ontological arguments.
Five Proofs of the Existence of God — Edward Feser
Classical (Aristotelian, Neo-Platonic, Thomistic) arguments defended in analytic form, with sustained attention to what the conclusions do and do not establish.
The Miracle of Theism — J. L. Mackie
The best twentieth-century atheist engagement with the theistic arguments; read it to see which objections actually bite.
Arguing About Gods — Graham Oppy
A rigorous skeptical assessment arguing that no theistic argument succeeds as a proof; the standard opposing benchmark.
The Existence of God — Richard Swinburne
Builds a cumulative probabilistic case rather than a single deductive proof — useful for seeing how arguments combine.