What is Justice? Justice, Law, and Politics in the Mirror of Science

The book argues that justice is a subjective, irrational ideal that cannot be objectively defined by rational science. Kelsen examines and rejects the major absolute doctrines of justice — Platonic, Aristotelian, and those found in the holy scriptures — showing that their formulas are empty and can justify any content. This position follows directly from the Pure Theory's separation of law from morality: since legal science must be pure of value considerations, the problem of justice lies outside its domain. The book is a collection of essays unified by this relativist critique, culminating in Kelsen's personal confession of his own justice.

Kelsen contends that natural law doctrines of absolute justice derive their norms from metaphysical authorities — God, nature, or reason — and serve to legitimize positive law that individuals are called to obey irresistibly. Because these absolute formulas are empty, they can be used to justify any existing order, contributing to the maintenance of the status quo. In this sense, jusnaturalism has played a historically conservative role. By contrast, Kelsen's relativist positivism holds that the value 'justice' is never absolute and must always be subjected to critical examination by autonomous moral agents.

Kelsen does not claim to define justice absolutely; he confesses what justice means for him. Since science is his profession and therefore the most important thing in his life, justice is found in that social order under whose protection the search for truth can prosper. His justice is the justice of freedom, the justice of democracy, and the justice of tolerance. This is a personal commitment rather than a scientific conclusion, consistent with his view that the individual, as an autonomous moral agent, must choose between competing value systems. Democracy, by privileging critical discussion, provides the only environment where this choice can be exercised freely.

The central criticism is that Kelsen's relativism, while rigorous in its critique of absolute doctrines, leaves no rational basis for choosing between competing value systems. If justice is ultimately a matter of personal commitment, as Kelsen's closing confession suggests, then his defense of democracy and tolerance appears to be a preference rather than a rational requirement. Critics from the natural law tradition argue that this makes his theory incapable of grounding resistance to unjust regimes. Kelsen's response is that legal validity is relative to a presupposed point of view, and that the choice between absolute and relative justice is itself an ethical decision that cannot be made by science.

The book is a companion to the Pure Theory rather than a departure from it. The Pure Theory separates legal science from morality and politics; What is Justice? explores the domain that the Pure Theory excludes, showing why justice cannot be the object of legal science. The essays were collected and published in 1957, three years before the second edition of Reine Rechtslehre, and substantial parts of the collection appeared in concentrated form as the section 'Das Problem der Gerechtigkeit' in the appendix to that second edition. The book thus fills the gap that the Pure Theory creates, addressing the question that the Pure Theory brackets.

The title poses the question that Kelsen refuses to answer in absolute terms. The subtitle 'Justice, Law, and Politics in the Mirror of Science' indicates the method: Kelsen examines these concepts through the lens of scientific analysis, which can describe what people believe about justice and how those beliefs function in law and politics, but cannot prescribe what justice objectively requires. The 'mirror' suggests that science reflects these concepts without transforming them into absolutes. The book is a collection of essays unified by this scientific attitude, applying critical analysis to the major historical doctrines of justice.