Ethics is the enquiry into how one should live. Two related questions identify its task: What is goodness? How ought one to act? It can usefully be defined as the attempt to answer the sceptic who asks: Why be moral?
As a systematic enquiry, ethics began in ancient Greece. Some of the Sophists argued that morality is a man-made convenience, and cannot therefore be binding; the rational course is to pursue one's own interests. Plato responded in the Republic that possession of virtues such as justice and courage promotes the good life, consisting of harmony in the soul. Virtue is knowledge: if one knows the good, one cannot do wrong. Aristotle disagreed; one can "know the better but do the worse"-weakness of will is a human failing. In his Nicoma-chean Ethics he argued that happiness is the aim of life, and is achieved by acting in accordance with reason, which teaches that the middle course in any action is best.
Chief among the later Greek schools were the Epicureans and Stoics. Epicurus held that pleasure (by which he meant friendship and discussion) is the highest good. Love, wine and feasting carry the seeds of pain, he said, so must be avoided. His austere views figure in Lucretius's On The Nature of Things. The Stoics taught indifference; what we cannot control we must accept, and what we can control-our passions and desires-we must subdue. The two great classics of Stoicism are Epictetus's Discourses and the Emperor Marcus Aurelius's Meditations.
Ethical thought changed character dramatically under Christianity. Belief in a divine lawgiver removes the need to enquire into the source and justification of ethical laws. But the great Christian moral philosophers-Augustine in The City of God (427 AD) and Thomas Aquinas in Summa Theologiae (1273)-nevertheless tried to marry Greek philosophy to Christian moral teaching. Under Aristotle's influence, Aquinas analysed human acts as those we have a reason to perform-the reason ultimately being to achieve happiness, which we do by fulfilling human purposes according to God-ordained natural laws.
Most Christian morality, however, took the form of casuistry: the painstaking interpretation of prescriptions and proscriptions-for example, when must one fast?
Is the Good good because God commands it, or does he command it because it is good? This question reveals the weakness of theological ethics. If the former, then ethics is based on arbitrary will; we have no better reason to obey it than if someone coerces us by threats to do such-and-such (which is how religious ethics works). Accordingly the philosophers of the early modern period returned to basics. Does morality arise from love of others, or of self? Is it the child of reason or of emotion?
Hobbes in Leviathan (1651) argued that morality stems from self-interest. In the state of nature, self-interest produces conflicts, so men gather into society, contracting to forgo some personal liberty for mutual advantage. In opposition to Hobbes's egoism, Butler in his Fifteen Sermons (1726) and Shaftesbury in Characteristics of Men, Manners, Opinions, Times (1711) argued that people are by nature altruistic; benevolence is the basis of morality.
The greatest moral philosophers of the 18th century are Hume and Kant. In his Enquiry Concerning the Principles of Morals (1751) Hume argues that the basis of morality is human sentiment, and in particular sympathy. In sharp contrast, Kant in The Groundwork of the Metaphysic of Morals (1785) gives reason this role. We must act, he says, according to those principles which reason identifies as everywhere applicable; universalisable statements of duty constitute the moral law.
In the hope of devising a simple and practical moral theory which anyone can apply, Bentham in his Introduction to the Principles of Morals and Legislation (1789) and John Stuart Mill in Utilitarianism (1861) followed Francis Hutcheson's "utilitarian" suggestion, offered in An Essay on the Nature and Conduct of the Passions and Affections (1728), that those actions are good which promote "the greatest happiness of the greatest number." While such views secured a hold on Anglo-Saxon minds, Nietzsche in his Genealogy of Morals (1887) was attacking Christian ethics as a slave morality, in which negative experiences such as suffering and poverty had been turned into virtues.
Twentieth century ethical debate is a Babel. GE Moore claimed in Principia Ethica (1903) that goodness is indefinable and that the chief goods are friendship and beauty. Logical positivists, such as AJ Ayer in Language, Truth and Logic (1936), held that moral assertions are meaningless. John Mackie in Ethics (1977) attempted to defend an ethics of "enlightened self-interest." Alasdair MacIntyre's After Virtue (1981) argues that the Greek sense of ethics as all-embracing has been lost in favour of a narrow, moralistic, modernist conception. Bernard Williams agrees; in Ethics and the Limits of Philosophy (1985) he blames Kant for restricting ethics to the moral questions of duty and obligation, and argues for a return to the broader Socratic question of what the good life is.
