Ethics and Moral Philosophy
Ethics is the philosophical study of morality.
It examines what is right and wrong, good and bad, just and unjust, and how we ought to live.
The field is conventionally divided into meta-ethics, normative ethics, and applied ethics.
Meta-ethics studies the nature and status of moral claims.
Normative ethics develops substantive theories of right action and good life.
Applied ethics addresses specific practical domains.
Political philosophy is closely linked to ethics throughout.
Meta-ethics
Meta-ethics investigates the semantics, metaphysics, epistemology, and psychology of morality.
Cognitivism vs non-cognitivism
Cognitivism holds that moral statements express beliefs that are truth-apt.
They can be true or false.
Non-cognitivism holds that moral statements do not express beliefs but other attitudes — emotions, prescriptions, plans.
Realism vs anti-realism
Cognitivist positions divide on whether moral statements are sometimes true.
Moral realism holds that moral statements are sometimes true, and their truth is mind-independent.
Variants include moral naturalism and non-naturalism.
Moral naturalism
Cornell realism is the leading naturalist variant.
Key works include Richard Boyd’s “How to Be a Moral Realist” (1988), Nicholas Sturgeon’s “Moral Explanations” (1985), and David Brink’s Moral Realism and the Foundations of Ethics (1989).
On this view, moral properties are natural properties identifiable a posteriori.
Ethics is continuous with science.
Non-naturalism
G. E. Moore’s Principia Ethica (1903) launched modern non-naturalism.
Contemporary defenders include Russ Shafer-Landau (Moral Realism: A Defence 2003) and Derek Parfit (On What Matters 2011).
Moral properties are sui generis, not reducible to natural facts.
Moore’s open question argument purported to show all naturalistic definitions of “good” fail.
Error theory
J. L. Mackie’s Ethics: Inventing Right and Wrong (1977) defended error theory.
Moral statements aim at truth but systematically fail; there are no objective values.
The argument from queerness (objective values would be metaphysically and epistemically odd) supports error theory.
The argument from disagreement (deep moral disagreement is best explained by absence of objective values) also supports it.
Constructivism
Constructivism holds that moral truths are constructed by rational agents through procedures of reflection and choice.
Key works: Christine Korsgaard’s The Sources of Normativity (1996) and Sharon Street’s “A Darwinian Dilemma for Realist Theories of Value” (Philosophical Studies 2006).
Constitutivism
Constitutivism holds that normative claims derive from constitutive features of agency itself.
See David Velleman’s How We Get Along (2009).
Non-cognitivist positions
Emotivism
A. J. Ayer’s Language, Truth and Logic (1936) and Charles Stevenson’s Ethics and Language (1944) defended emotivism.
Moral statements express emotions: “Boo!” or “Hooray!”
Prescriptivism
R. M. Hare’s The Language of Morals (1952) and Moral Thinking (1981) defended prescriptivism.
Moral statements are universalizable prescriptions.
Expressivism
Simon Blackburn’s Spreading the Word (1984) and Ruling Passions (1998) defend expressivism.
Allan Gibbard’s Wise Choices, Apt Feelings (1990) and Thinking How to Live (2003) develop a sophisticated version.
Moral statements express conative or planning states.
Quasi-realism (Blackburn) aims to vindicate ordinary realist talk on an expressivist base.
Moral psychology and motivation
Internalism about motivation holds that moral judgment intrinsically motivates.
See Michael Smith’s The Moral Problem (1994).
Externalism holds that moral judgment requires a separate desire to motivate (Brink, Mele).
The Humean theory of motivation holds that only beliefs plus desires motivate.
Moral beliefs alone do not motivate on the Humean view.
The Frege-Geach problem (P. T. Geach 1965) challenged emotivism.
How do moral terms function in unasserted contexts (conditionals, disjunctions) if they express attitudes?
Normative ethics
Three main families of substantive moral theory dominate.
1. Consequentialism
Consequentialism evaluates actions by their consequences.
Classical utilitarianism is the dominant form.
Bentham
Jeremy Bentham’s An Introduction to the Principles of Morals and Legislation (1789) introduced the principle of utility.
Act so as to maximize aggregate happiness.
The hedonic calculus quantifies pleasures by intensity, duration, certainty, propinquity, fecundity, purity, and extent.
Mill
John Stuart Mill’s Utilitarianism (1861) refined the doctrine.
Mill defended qualitative distinctions among pleasures.
His slogan: “better to be a human being dissatisfied than a pig satisfied.”
He offered a “proof” of utilitarianism in chapter IV.
Sidgwick
Henry Sidgwick’s The Methods of Ethics (1874) gave the most rigorous utilitarian treatment.
He identified intuitive, egoistic, and utilitarian methods.
He addressed the “dualism of practical reason” — the conflict between self-interest and impartial benevolence.
Modern variations
Act vs rule utilitarianism: evaluate individual acts vs general rules.
Indirect utilitarianism: adopt non-utilitarian decision procedures because they best maximize utility.
Hare’s two-level theory: intuitive level for everyday life, critical level for reflection.
Preference utilitarianism (Hare, John Harsanyi): maximize preference satisfaction rather than hedonic state.
Negative utilitarianism (attributed to Popper in The Open Society and Its Enemies 1945): minimize suffering rather than maximize happiness.
Total view vs average view in population ethics: total favors more lives barely worth living; average favors fewer well-off lives.
Derek Parfit (Reasons and Persons 1984 part IV) raised the Repugnant Conclusion and Mere Addition Paradox.
Scalar consequentialism (Norcross) and satisficing (Slote) reject the maximizing requirement.
2. Deontology
Deontological ethics evaluates actions by conformity to duty or rules, independent of consequences.
Kant
Immanuel Kant wrote Groundwork of the Metaphysics of Morals (1785), Critique of Practical Reason (1788), and Metaphysics of Morals (1797).
The categorical imperative is formulated three (or four) ways.
The Formula of universal law: act only on that maxim by which you can at the same time will it to be a universal law of nature.
The Formula of humanity: act so as to treat humanity, whether in your own person or in another, always as an end and never merely as a means.
The Formula of autonomy / kingdom of ends: act as if a member of a kingdom of ends, both legislator and subject of universal law.
Kant distinguished perfect duties (admit no exception — do not lie, do not murder) from imperfect duties (require a general policy — beneficence, self-development).
The good will is the only unconditional good.
Ross
W. D. Ross’s The Right and the Good (1930) introduced prima facie (or pro tanto) duties.
The seven duties: fidelity, reparation, gratitude, justice, beneficence, self-improvement, non-maleficence.
They can conflict, and judgment is required in particular cases.
Contemporary deontology
Christine Korsgaard’s The Sources of Normativity (1996) defends a Kantian constructivism grounded in the agent’s practical identity.
Onora O’Neill’s Constructions of Reason (1989) advances Kantian constructivism with attention to non-ideal conditions.
Frances Kamm’s Morality, Mortality (1993, 1996) and Intricate Ethics (2007) work in the deontological tradition on doing/allowing, intending/foreseeing, and aggregation puzzles.
Contractualism
T. M. Scanlon’s What We Owe to Each Other (1998) defends contractualism.
An action is wrong if it would be disallowed by any set of principles for the general regulation of behavior that no one could reasonably reject.
3. Virtue ethics
Virtue ethics focuses on character — what kind of person to be.
Aristotle
Aristotle’s Nicomachean Ethics (c. 340 BCE) is the founding text.
Eudaimonia (flourishing) is the highest human good.
It is achieved through activity in accordance with virtue (arete).
Virtues are stable character traits — dispositions to feel and act appropriately.
Moral virtue is the mean between deficiency and excess (courage between cowardice and rashness).
Phronesis (practical wisdom) guides perception in particular cases.
Friendship and the contemplative life are central.
Twentieth-century revival
G. E. M. Anscombe’s “Modern Moral Philosophy” (Philosophy 1958) attacked deontology and consequentialism and called for return to virtue.
Alasdair MacIntyre’s After Virtue (1981) diagnosed modern moral philosophy as a wreckage of incompatible fragments.
MacIntyre called for return to a tradition-based Aristotelian virtue ethics.
Philippa Foot’s Virtues and Vices (1978) and Natural Goodness (2001) defended naturalistic neo-Aristotelian virtue ethics.
Bernard Williams’s Ethics and the Limits of Philosophy (1985) criticized the “morality system” of Kantianism and utilitarianism.
He emphasized character and integrity.
Rosalind Hursthouse’s On Virtue Ethics (1999) developed a contemporary neo-Aristotelian theory of right action.
An action is right iff a virtuous agent would do it.
Michael Slote’s Morals from Motives (2001) defends agent-based virtue ethics focused on motives.
Julia Annas’s Intelligent Virtue (2011) analogizes virtue to a practical skill.
Applied ethics
Bioethics
Bioethics emerged in the 1970s in response to medical research scandals (Tuskegee 1932-1972), new technologies (organ transplantation, ICUs), and reproductive technology.
The four principles
Beauchamp and Childress’s Principles of Biomedical Ethics (1979, 8th ed. 2019) established the four-principles framework:
- Autonomy — respect for self-determination
- Beneficence — promote well-being
- Non-maleficence — do no harm (primum non nocere)
- Justice — fair distribution of benefits and burdens
Informed consent
The Nuremberg Code (1947), Declaration of Helsinki (1964), and Belmont Report (1979) anchor research ethics.
Abortion
Judith Jarvis Thomson’s “A Defense of Abortion” (Philosophy and Public Affairs 1971) introduces the violinist analogy.
Don Marquis’s “Why Abortion Is Immoral” (Journal of Philosophy 1989) offers the future-like-ours argument.
Michael Tooley’s “Abortion and Infanticide” (1972) and Mary Anne Warren’s “On the Moral and Legal Status of Abortion” (1973) address personhood criteria.
Euthanasia and assisted dying
James Rachels’s “Active and Passive Euthanasia” (NEJM 1975) challenged the standard distinction.
Peter Singer’s Practical Ethics (1979) and Daniel Callahan’s Setting Limits (1987) frame ongoing debates.
Reproductive technologies
ART, surrogacy, cloning, and gene editing raise new questions.
The He Jiankui CRISPR babies (2018) provoked an international moratorium on germline editing.
Organ donation and xenotransplantation
Pig-to-human heart transplants since 2022 raise new questions about cross-species transfer and animal welfare.
AI in medicine
Diagnostic algorithms, autonomous surgery, predictive risk scores raise questions of liability, transparency, and bias.
Animal ethics
Peter Singer’s Animal Liberation (1975) gives a utilitarian argument from equal consideration of interests.
Speciesism is analogous to racism on this view.
Tom Regan’s The Case for Animal Rights (1983) defends a rights-based view.
Subjects-of-a-life have inherent value.
Christine Korsgaard’s Fellow Creatures: Our Obligations to the Other Animals (2018) extends Kantian ethics to animals.
Martha Nussbaum’s Frontiers of Justice (2006) develops the capabilities approach for animals.
Environmental ethics
Aldo Leopold’s A Sand County Almanac (1949) articulates the land ethic.
His maxim: “A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community.”
Arne Naess’s “The Shallow and the Deep, Long-Range Ecology Movement” (Inquiry 1973) defends deep ecology and biocentric egalitarianism.
Paul Taylor’s Respect for Nature (1986) defends biocentric individualism — each living being has inherent worth.
James Lovelock’s Gaia: A New Look at Life on Earth (1979) advances the Gaia hypothesis.
Climate ethics
Stephen Gardiner’s A Perfect Moral Storm (2011) diagnoses climate change as the convergence of multiple ethical challenges.
Henry Shue’s Climate Justice (2014), John Broome’s Climate Matters (2012), Dale Jamieson’s Reason in a Dark Time (2014), and Sara Doan’s recent work address intergenerational justice.
Business ethics
Stakeholder theory — R. Edward Freeman’s Strategic Management: A Stakeholder Approach (1984).
Corporate social responsibility — Carroll’s pyramid (economic, legal, ethical, philanthropic) 1991.
Kantian business ethics — Norman Bowie’s Business Ethics: A Kantian Perspective (1999).
Agency theory and the shareholder vs stakeholder debate (Friedman 1970 vs Freeman 1984).
Effective altruism and longtermism
Peter Singer’s “Famine, Affluence, and Morality” (Philosophy and Public Affairs 1972) and The Life You Can Save (2009) launched the effective altruism movement.
William MacAskill (formerly Crouch) wrote Doing Good Better (2015) and What We Owe the Future (2022).
He defends longtermism — the view that positively influencing the long-term future is a key moral priority.
Toby Ord’s The Precipice (2020) addresses existential risk and humanity’s long-term potential.
Political philosophy
Political philosophy addresses legitimacy, justice, rights, equality, freedom, and the state.
Classical and modern foundations
Plato’s Republic (c. 375 BCE) — the just city and the just soul; philosopher-kings.
Aristotle’s Politics (c. 340 BCE) — humans are political animals; constitutional types.
Thomas Hobbes’s Leviathan (1651) — state of nature is solitary, poor, nasty, brutish, and short; social contract creates absolute sovereign.
John Locke’s Two Treatises of Government (1689) — natural rights to life, liberty, property; consent of the governed; right of revolution.
Jean-Jacques Rousseau’s The Social Contract (1762) — general will; “Man is born free, and everywhere he is in chains.”
Edmund Burke’s Reflections on the Revolution in France (1790) — conservative response.
Immanuel Kant’s Perpetual Peace (1795) and Metaphysics of Morals (1797) — republican government, cosmopolitan right.
G. W. F. Hegel’s Philosophy of Right (1820) — family, civil society, state.
John Stuart Mill’s On Liberty (1859) — harm principle; freedom of thought and expression.
Karl Marx’s The Communist Manifesto (1848, with Engels) and Capital vol. 1 (1867) — historical materialism; critique of capitalism; class struggle.
Contemporary
Rawls
John Rawls’s A Theory of Justice (1971) and Political Liberalism (1993) reshaped the field.
The veil of ignorance generates two principles of justice.
First: equal basic liberties.
Second: social and economic inequalities arranged to (a) the greatest benefit of the least advantaged (difference principle) and (b) attached to positions open under fair equality of opportunity.
Nozick
Robert Nozick’s Anarchy, State, and Utopia (1974) defends libertarian entitlement theory.
The minimal state is justified.
The Wilt Chamberlain argument challenges patterned distributions.
Capabilities approach
Amartya Sen’s The Idea of Justice (2009) and Martha Nussbaum’s Creating Capabilities (2011) develop the capabilities approach.
Justice concerns the real freedoms (capabilities) people have to do and be.
Communitarianism
Alasdair MacIntyre’s After Virtue (1981), Michael Walzer’s Spheres of Justice (1983), Michael Sandel’s Liberalism and the Limits of Justice (1982) and Justice (2009), and Charles Taylor’s Sources of the Self (1989) develop communitarian critiques of liberalism.
Critical theory of race and gender
Charles Mills’s The Racial Contract (1997), Carole Pateman’s The Sexual Contract (1988), Anne Phillips’s The Politics of Presence (1995), and Iris Marion Young’s Justice and the Politics of Difference (1990) develop critical perspectives.
Global justice
Thomas Pogge’s World Poverty and Human Rights (2002) and David Miller’s National Responsibility and Global Justice (2007) address cross-border obligations.
AI ethics and alignment
A rapidly developing area combining technical AI safety with applied ethics.
Early fiction
Isaac Asimov’s three laws of robotics (1942) in I, Robot stories anticipated machine ethics.
Bostrom
Nick Bostrom’s Superintelligence (2014) developed the orthogonality thesis, instrumental convergence, and the control problem.
Russell
Stuart Russell’s Human Compatible (2019) advocates beneficial AI through uncertainty about human preferences and inverse reward design.
Technical alignment
Work by Paul Christiano (iterated amplification, RLHF), Evan Hubinger (mesa-optimization, Risks from Learned Optimization 2019), MIRI, OpenAI alignment team, Anthropic (Constitutional AI Bai et al. 2022), ARC, and DeepMind safety addresses alignment problems.
Fairness and bias
Joy Buolamwini’s Gender Shades (2018) addresses facial recognition bias and founded the Algorithmic Justice League.
Kate Crawford’s Atlas of AI (2021), Safiya Noble’s Algorithms of Oppression (2018), and Cathy O’Neil’s Weapons of Math Destruction (2016) address systemic issues.
LLM ethics
Emily Bender et al.’s “On the Dangers of Stochastic Parrots” (FAccT 2021) catalogues risks of large language models.
Moral status of AI
Eric Schwitzgebel and Mara Garza’s “A Defense of the Rights of Artificial Intelligences” (Midwest Studies in Philosophy 2015), Jeff Sebo’s work on AI moral status (2024), and Schwitzgebel and Garrett (2024) address questions raised by LaMDA, Claude, and GPT models.
The trolley problem and moral dilemmas
The trolley problem began as a footnote in Philippa Foot’s “The Problem of Abortion and the Doctrine of the Double Effect” (Oxford Review 1967).
Judith Jarvis Thomson developed it in “Killing, Letting Die, and the Trolley Problem” (The Monist 1976) and “The Trolley Problem” (Yale Law Journal 1985).
Standard cases
Bystander/switch case: a runaway trolley will kill five; you can divert it to kill one.
Most respondents say this is permissible.
Footbridge case: you can stop the trolley by pushing a large man off a bridge into its path, killing him to save five.
Most say impermissible.
The puzzle
Why is the difference moral if both involve trading one death for five?
Doctrine of double effect, doing/allowing, intending/foreseeing, and use-as-means analyses have all been proposed.
Empirical work
Joshua Greene’s fMRI studies (“An fMRI Investigation of Emotional Engagement in Moral Judgment” Science 2001) showed emotional brain regions activate more for personal force cases.
John Mikhail and others have explored implicit moral grammars.
Moral psychology and experimental ethics
Kohlberg
Lawrence Kohlberg’s The Philosophy of Moral Development (1981) describes six stages of moral development.
The three levels are pre-conventional, conventional, and post-conventional.
The stages are based on responses to dilemmas like the Heinz dilemma (steal a drug to save a wife’s life).
Gilligan
Carol Gilligan’s In a Different Voice (1982) criticized Kohlberg as gender-biased.
Care ethics emphasizes relationships and responsibility.
Haidt
Jonathan Haidt’s The Righteous Mind (2012) develops moral foundations theory.
The six foundations: care/harm, fairness/cheating, loyalty/betrayal, authority/subversion, sanctity/degradation, liberty/oppression.
The intuitionist model holds that judgment precedes reasoning (“elephant and rider”).
Greene
Joshua Greene’s Moral Tribes (2013) defends a dual-process model.
Intuitive deontological responses are paired with deliberative utilitarian responses.
Knobe
Joshua Knobe identified the Knobe effect (2003): asymmetry in intentional action attribution for harmful vs helpful side effects.
He founded experimental philosophy (X-Phi).
Bloom
Paul Bloom’s Just Babies (2013) addresses infant moral cognition.
Infants show rudimentary preferences for helpers over hinderers.
Decety
Jean Decety has developed neuroscience of empathy and morality.
Recent figures
The current generation of leading moral philosophers includes the following.
Derek Parfit (1942-2017) — Reasons and Persons (1984), On What Matters (3 vols, 2011, 2017); argued for moral realism, convergence of Kantian, contractualist, and consequentialist theories.
Thomas Nagel — The View from Nowhere (1986), Mortal Questions (1979); objectivity and subjectivity in ethics.
T. M. Scanlon — What We Owe to Each Other (1998); contractualism.
Peter Singer — prolific applied ethics.
Martha Nussbaum — capabilities approach, emotion in ethics.
Amartya Sen — development economics and ethics.
Michael Sandel — The Tyranny of Merit (2020).
Christine Korsgaard — Kantian constructivism.
Patricia Churchland — Braintrust (2011); neurobiological account of morality.
Sharon Street — Darwinian dilemma for moral realism.
Allan Gibbard — expressivism and normative concepts.
Care ethics and feminist ethics
Care ethics emerged from Carol Gilligan’s developmental psychology critique.
Nel Noddings’s Caring: A Feminine Approach to Ethics and Moral Education (1984) developed care ethics as a substantive normative theory.
Care is the primordial ethical relation.
Virginia Held’s The Ethics of Care (2006) systematized the approach.
Joan Tronto’s Moral Boundaries (1993) extended care ethics to political theory.
Feminist ethics more broadly includes Susan Moller Okin’s Justice, Gender, and the Family (1989) and Martha Nussbaum’s work on women’s capabilities.
Disability ethics
Disability ethics challenges standard frameworks.
Eva Feder Kittay’s Love’s Labor (1999) raises dependency as central.
Elizabeth Barnes’s The Minority Body (2016) defends a mere-difference view of disability.
Non-Western ethical traditions
This library will catalog non-Western ethics in later notes.
These include Confucian virtue ethics (Analects; Mencius; Xunzi), Daoist naturalism (Zhuangzi; Laozi), Buddhist ethics (Eightfold Path; Buddhaghosa; Shantideva), Hindu dharma ethics (Bhagavad Gita; Manusmriti), African ubuntu ethics (Mbiti; Wiredu), and Islamic ethics (Al-Ghazali; Miskawayh).
Comparative ethics is an active area linking these to Western normative traditions.