Preface

Moral philosophy owes the public more than a history of its disagreements. It owes an account of what we know about right and wrong, why we are justified in believing it, and how that knowledge should guide conduct. We know enough to do better than we are doing. The fact that we do not know everything is no excuse for failing to use what we know.

Consider moral relativism and moral exceptionalism. Moral relativism makes moral rightness ultimately relative to the standards of a person or community, denying a common basis on which those standards themselves can be judged. Moral exceptionalism claims the authority of moral rules while reserving unjustified exemptions for oneself or one’s favored group. The relativist denies that a common standard can adjudicate between conflicting outlooks. The exceptionalist demands a common standard but refuses to be bound by it.

Philosophers routinely explain what is wrong with these positions. A society’s acceptance of a practice does not establish its rightness. A person’s identity or allegiance does not entitle them to an exemption from a rule they impose on others. Differences in circumstances can justify different treatment; merely being the person who benefits cannot. These are familiar requirements of moral justification, not discoveries awaiting some future breakthrough.

Yet philosophy is commonly presented primarily as a method of inquiry: questioning assumptions, making distinctions, and testing arguments. Those practices are indispensable. They should also produce knowledge. A discipline ought to be able to explain not only how its practitioners investigate questions, but what their investigations have established.

Over the centuries, inquiries pursued within philosophy have developed into independent disciplines that accumulate findings, teach them, and put them to work. Their knowledge remains revisable, but revision is possible precisely because there is something established to revise. Moral philosophy needs that same cumulative ambition. Remaining within philosophy should not mean remaining forever at the beginning. Some of moral philosophy’s results already meet that standard; the requirements of justification just described are among them.

The consequences of failing to fulfill that ambition extend far beyond the academy. Corruption, exploitation, persecution, and genocide proceed amid abundant declarations of righteousness. Religious conviction, inherited belief, and moral intuition supply assurances that can be as intense as they are incompatible. Meanwhile, those with sufficient power can treat their ability to impose an outcome as though it justified imposing it.

The people subjected to these decisions need something better. They should not have to share a ruler’s religion, a majority’s intuitions, or an institution’s traditions before being entitled to challenge what is being done to them. They need reasons whose authority does not depend on the permission of those they challenge.

For a discipline concerned with right and wrong, this is an emergency within its own field of responsibility. Persistent disagreement is a problem to be worked on, not an adequate public answer.

We need something like a standard model of morality: a body of justified knowledge that people can use while philosophers continue to improve it. Scientific inquiry does not wait for a final theory of everything before putting established knowledge to work. Moral philosophy should not demand finality as the price of usefulness. It should explain where its conclusions are secure, where uncertainty matters, and how further inquiry can improve the answers. Difficulties at the frontier should direct research, not suspend the authority of everything already established.

R. M. Hare believed the world would be better if philosophers gave morality a firmer rational footing. For him, the justification of moral judgment mattered because of what people did to one another. This book returns to his work in that spirit. Its purpose is not to win a place for another theory in a catalogue of theories. It is to recover an intellectual achievement that can help us judge and act more responsibly.

Whether Hare completed the foundations of morality remains a question for philosophical argument. Whether we know enough to do better right now is not in serious doubt.

This book begins to explain what we know and how we know it.