Ethical theory and moral reasoning across the major philosophical traditions. Covers normative ethics (consequentialism, deontology, virtue ethics, care ethics, existentialist ethics), metaethics (moral realism, anti-realism, emotivism, error theory), and applied ethics (bioethics, environmental ethics, AI ethics, just war theory). Includes a moral dilemma analysis framework with worked examples applying multiple frameworks to the same case.
Ethics is the branch of philosophy that asks how we ought to live and what makes actions right or wrong. It is not merely a catalog of rules — it is the systematic investigation of the grounds for moral judgment. This skill covers the major normative theories, metaethical positions, applied ethical domains, and a structured framework for analyzing moral dilemmas.
Agent affinity: kant (ethics, Sonnet), beauvoir (existentialism and phenomenology, Opus)
Concept IDs: philo-ethical-frameworks, philo-virtue-ethics, philo-applied-ethics
| # | Domain | Core question | Key thinkers |
|---|---|---|---|
| 1 | Consequentialism | What produces the best outcomes? | Bentham, Mill, Singer |
| 2 | Deontological ethics | What duties and rules must we follow? | Kant, Ross, Scanlon |
| 3 | Virtue ethics | What kind of person should I be? | Aristotle, MacIntyre, Foot |
| 4 |
| Care ethics |
| What do our relationships require? |
| Gilligan, Noddings, Held |
| 5 | Existentialist ethics | How do I create meaning through choice? | Beauvoir, Sartre, Kierkegaard |
| 6 | Metaethics | What is the nature of moral claims? | Ayer, Mackie, Moore, Hare |
| 7 | Applied ethics | What should we do in specific domains? | Thomson, Leopold, Bostrom |
Core idea. An action is morally right if and only if it produces the best overall consequences. The rightness of an act depends entirely on its outcomes, not on the intentions behind it or the nature of the act itself.
Bentham's hedonic calculus. Jeremy Bentham (1748-1832) proposed that the right action maximizes total pleasure and minimizes total pain, calculated across all affected parties. He identified seven dimensions: intensity, duration, certainty, propinquity (nearness in time), fecundity (tendency to produce further pleasures), purity (freedom from pain), and extent (number affected).
Mill's qualitative distinction. John Stuart Mill (1806-1873) argued that Bentham's calculus was too crude — some pleasures are qualitatively higher than others. "It is better to be Socrates dissatisfied than a fool satisfied." Mill introduces the competent judge test: anyone who has experienced both higher and lower pleasures will prefer the higher.
Worked example — The transplant surgeon:
A surgeon has five patients dying from organ failure. A healthy visitor arrives for a routine checkup. Harvesting the visitor's organs would save five lives at the cost of one.
Act utilitarian analysis: Five lives saved vs. one lost — the calculus favors harvesting. But this ignores second-order effects: if surgeons routinely harvested patients, nobody would visit hospitals, producing catastrophically worse outcomes.
Rule utilitarian analysis: The rule "surgeons may kill patients to harvest organs" would, if generally followed, destroy trust in medicine. The rule maximizing overall utility is "surgeons must not harm patients" — so the surgery is wrong.
This case demonstrates why most sophisticated consequentialists are rule utilitarians or incorporate indirect effects.
Peter Singer (1946-) extends utilitarian reasoning globally: if we can prevent suffering without sacrificing anything of comparable moral importance, we ought to do so. His "drowning child" thought experiment — would you ruin a $200 suit to save a drowning child? — argues that geographical distance is morally irrelevant, so we are obligated to donate to effective charities.
Core idea. Some actions are inherently right or wrong, independent of their consequences. Morality consists in following rules, duties, or principles that respect the dignity and autonomy of persons.
Immanuel Kant (1724-1804) grounded morality in pure reason, not consequences or feelings.
The categorical imperative — first formulation (universalizability): "Act only according to that maxim by which you can at the same time will that it should become a universal law."
Worked example — Lying promises:
Can I make a promise I intend to break?
The categorical imperative — second formulation (humanity as end): "Act so that you treat humanity, whether in your own person or in that of another, always as an end and never merely as a means."
This forbids treating people as mere instruments. Slavery, deception, and coercion all violate this formulation because they bypass the autonomous will of the person acted upon.
The kingdom of ends. Kant envisions a community of rational agents, each legislating moral laws that all could accept. This anticipates Rawls's original position and Scanlon's contractualism.
W. D. Ross (1877-1971) rejected Kant's absolutism while preserving the deontological framework. He proposed seven prima facie duties — duties that hold unless overridden by a stronger duty:
When duties conflict, moral judgment — not a formula — determines which prevails. This captures the phenomenology of moral experience better than single-principle theories.
Core idea. Ethics is not primarily about actions or rules but about character. The central question is not "What should I do?" but "What kind of person should I be?"
Aristotle (384-322 BCE) argued that the good life (eudaimonia — often translated "happiness" but better rendered "flourishing" or "living well") consists in the exercise of virtue (arete) in accordance with reason.
The doctrine of the mean. Every virtue is a mean between two vices — one of excess and one of deficiency:
| Deficiency (vice) | Mean (virtue) | Excess (vice) |
|---|---|---|
| Cowardice | Courage | Rashness |
| Insensibility | Temperance | Self-indulgence |
| Stinginess | Generosity | Prodigality |
| Self-deprecation | Truthfulness | Boastfulness |
| Boorishness | Wit | Buffoonery |
| Quarrelsomeness | Friendliness | Obsequiousness |
The mean is not an arithmetic midpoint — it is the right amount, at the right time, toward the right people, for the right reason. This requires phronesis (practical wisdom), which can only be developed through experience and habituation.
Worked example — Courage in the face of a difficult truth:
A doctor must tell a patient that their condition is terminal. The coward avoids the conversation entirely. The rash person delivers the news bluntly without care. The courageous doctor finds the right moment, speaks honestly but with compassion, and remains present to support the patient. The virtue lies not in a formula but in the character of the agent who perceives the situation rightly.
Alasdair MacIntyre (1929-) diagnosed modernity as suffering from moral fragmentation — we have inherited disconnected fragments of ethical vocabularies from incompatible traditions. His solution: ground virtues in social practices, narrative identity, and moral traditions. A virtue is a quality that enables a person to excel within practices, sustain a coherent life narrative, and contribute to the moral tradition of their community.
Philippa Foot (1920-2010) argued that moral goodness is natural goodness — just as a plant with strong roots and healthy leaves is a good specimen of its kind, a human being who exhibits courage, justice, and temperance is a good specimen of the human species. This grounds virtue ethics in a naturalistic framework without reducing ethics to biology.
Core idea. Morality arises from concrete relationships and responsibilities, not abstract principles. The fundamental moral experience is not detached reasoning but engaged caring.
Carol Gilligan (1936-) challenged Lawrence Kohlberg's stage theory of moral development, arguing that it privileged a "justice orientation" (rules, rights, fairness) associated with masculine socialization while devaluing a "care orientation" (relationships, responsibility, responsiveness) more common in women's moral experience. Her work did not claim that care ethics is exclusively female but that the care perspective had been systematically excluded from moral philosophy.
Nel Noddings (1929-2022) developed care ethics as a full-fledged theory. Caring is a relation between a carer and a cared-for. The carer attends to the cared-for with "engrossment" (receptive attention) and "motivational displacement" (motivation shifted toward the other's needs). The cared-for recognizes and responds to the caring. This relational structure cannot be captured by universal principles.
Worked example — Care ethics on elder care:
An adult child must decide whether to place their aging parent in a facility. A purely utilitarian calculation might favor the facility (more efficient care, less burden on the child). A Kantian analysis might focus on duty and autonomy. Care ethics asks: What does this particular relationship require? What has this parent done for this child? What does attentive, responsive caring look like in this specific situation? The answer may not generalize — it depends on the history, quality, and dynamics of the relationship.
Core idea. There are no pre-given moral truths — we create values through our choices. This radical freedom entails radical responsibility.
Simone de Beauvoir (1908-1986) argued that human existence is fundamentally ambiguous — we are simultaneously free and situated, subjects and objects, individual and social. Authentic ethical life consists in embracing this ambiguity rather than fleeing into bad faith.
Beauvoir identified several forms of bad faith:
Authentic ethics requires willing one's own freedom AND the freedom of others. Oppression is the fundamental ethical wrong because it denies freedom.
Jean-Paul Sartre (1905-1980) declared that existence precedes essence — we are not born with a fixed nature or purpose. "Man is condemned to be free." Every choice defines who we are, and we cannot escape this responsibility by appealing to God, nature, or society.
Worked example — Sartre's student:
During World War II, a student asks Sartre for advice. The student's brother has been killed by the Germans, and he feels called to join the Resistance. But his mother depends on him, and leaving would devastate her. What should he do?
Sartre's answer: No ethical theory can tell you. Kant's categorical imperative gives no clear answer — both "honor your mother" and "fight for justice" can be universalized. Utilitarianism cannot calculate the consequences of either choice with any certainty. The student must simply choose — and in choosing, define what kind of person he is. The anguish of the choice IS the ethical experience.
Core idea. Metaethics asks not "What should I do?" but "What do moral claims mean? Are they true? Can they be justified?"
| Position | Claim | Key thinker |
|---|---|---|
| Moral realism | Moral facts exist independently of what anyone thinks | Moore, Shafer-Landau |
| Moral anti-realism | There are no mind-independent moral facts | Mackie, Blackburn |
| Emotivism | Moral statements express emotions, not propositions | Ayer, Stevenson |
| Prescriptivism | Moral statements are universal prescriptions | Hare |
| Error theory | Moral statements are truth-apt but systematically false | Mackie |
| Constructivism | Moral truths are constructed by rational agents | Korsgaard, Scanlon |
| Moral naturalism | Moral properties are natural properties | Railton, Boyd |
| Moral non-naturalism | Moral properties are real but not natural | Moore (open question argument) |
Worked example — Moore's open question argument (1903):
Suppose someone claims "good" means "that which produces pleasure." Moore asks: "This action produces pleasure, but is it good?" This question is intelligible and open — it makes sense to ask it. But if "good" simply meant "pleasure-producing," the question would be as trivial as "This bachelor is unmarried, but is he unmarried?" Since it isn't trivial, "good" does not mean "pleasure-producing." This argument applies to any proposed naturalistic definition of goodness.
Worked example — Mackie's argument from queerness (1977):
J. L. Mackie argued that if objective moral values existed, they would be utterly unlike anything else in the universe — "qualities or relations of a very strange sort, utterly different from anything else." They would need to be intrinsically motivating (knowing them would automatically compel action), which no natural property does. The implausibility of such entities gives us reason to deny their existence. This is a metaphysical argument for error theory.
Central questions: Is euthanasia permissible? What are the ethics of genetic engineering? When does personhood begin? Who should receive scarce medical resources?
The four principles (Beauchamp and Childress):
Central questions: Do non-human animals have moral standing? Do ecosystems? Do future generations have rights?
Leopold's land ethic: "A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise." This extends moral consideration beyond humans to the ecological community as a whole.
Singer's animal liberation: If suffering is morally relevant (as any utilitarian must hold), and animals suffer, then their suffering counts equally with human suffering of the same intensity.
Central questions: Can AI systems be moral agents? Who is responsible when an AI causes harm? Should AI systems be designed to follow deontological rules, maximize utility, or embody virtues?
The alignment problem: How do we ensure that AI systems pursue goals aligned with human values when those values are complex, contested, and often contradictory? This is not merely a technical problem — it is a deeply philosophical one about the nature of values themselves.
Two domains:
When confronting a moral dilemma, use this structured approach:
Who is affected? What are their interests, rights, and vulnerabilities?
Run the dilemma through at least three ethical lenses:
Do the frameworks agree? Where do they diverge? The divergence points reveal what is genuinely difficult about the case.
Does any framework's conclusion strike you as clearly wrong? Moral intuitions are not infallible, but persistent intuitive resistance to a conclusion is evidence that something in the analysis needs reexamination.
Choose a course of action and articulate your reasons clearly enough that others can evaluate them.
Worked example — The trolley problem (full analysis):
A runaway trolley will kill five people on the track. You can pull a lever to divert it to a side track where it will kill one person. Should you pull the lever?
Stakeholders: Five people on the main track, one person on the side track, you (the agent).
Consequentialist: Pull the lever. Five lives saved at the cost of one. Net benefit: +4 lives.
Kantian: More complex. Can you universalize "redirect lethal threats to minimize casualties"? Arguably yes. But the second formulation raises concerns — are you using the one person merely as a means? In the standard trolley case, the one person is not used as a means (they are a side effect, not an instrument). So Kant likely permits pulling the lever. (Contrast with the "fat man" variant, where you push someone onto the tracks — here they ARE used as a means.)
Virtue ethics: A courageous and just person would act to save the greater number when the cost is borne as a side effect rather than as an instrumentalization of a person. Pulling the lever is consistent with practical wisdom.
Care ethics: Who are these people to you? The abstract numbers may feel different if the one person on the side track is your child. Care ethics resists treating the scenario as a math problem.
Reflection: The frameworks largely agree on the standard trolley case but diverge sharply on variants (the fat man, the transplant surgeon). This reveals that the operative moral intuition is about the distinction between killing as a side effect and killing as a means — the doctrine of double effect.