British philosopher; the most consequential English-language moral philosopher of the second half of the 20th century in the judgment of many of his peers. Williams held chairs at Cambridge, Berkeley, and Oxford, served on a string of major British public commissions (on obscenity, on gambling, on drugs), and across forty years produced a body of work that did more than any other to make the prevailing philosophical consensuses of his time look provincial.
His sustained target was moral philosophy as system — the attempt, characteristic of both utilitarianism and Kantianism, to derive a universal decision procedure for action from a few abstract principles. Williams argued that this project misdescribes the moral life. Utilitarianism: For and Against (1973, with J.J.C. Smart) introduced his famous arguments from "integrity": utilitarianism's demand that one always perform the act that maximizes aggregate welfare overrides the agent's "ground projects," the commitments that make the agent's life one life rather than a node in an impersonal calculation. Ethics and the Limits of Philosophy (1985) extended the critique to all "morality" in the narrow modern sense — the system of obligation, blame, and the "moral ought" — arguing that the older Greek vocabulary of the ethical (the good life, virtues, practical wisdom) is more honest about what we actually face. He preferred thick ethical concepts (cruel, brave, treacherous, kind), which combine description and evaluation in ways that resist the systematizing analysis modern moral philosophy demands of them.
Williams's other great theme was the recovery of an honest historical sense within philosophy: Shame and Guilt (1993) read the Greeks as offering an ethical psychology in some respects superior to the modern one; Truth and Truthfulness (2002) defended the value of truth against contemporary debunkers while showing how historically contingent its institutional forms are. In the Beginning Was the Deed (2005) collected his political essays — including the influential argument for "political realism," the view that political philosophy must begin from the actual problem of legitimate order rather than from idealized first principles. He was a critic of utilitarianism but not a critic from outside the tradition: he took its moral seriousness seriously, which is why his arguments wounded.