Can we find a rational foundation for justice without relying on absolute, universal truths?

Ideas & Philosophy · Published 3 October 2026 Swipe more like this →

In short: Chaïm Perelman, a 20th-century Belgian philosopher, argued that because law and ethics rely on value judgments, they cannot be reduced to pure logic. By reviving ancient rhetoric, he developed a theory of argumentation that accounts for human contingency, persuasion, and the diverse audiences that shape our shared social reality.

Born in Warsaw in 1912, Chaïm Perelman moved to Belgium in 1925 and became a central figure at the Université Libre de Bruxelles. His early work was rooted in logical positivism, but a 1944 study on justice led him to a startling conclusion: if value judgments are essential to practical reasoning, yet cannot be subjected to the rigid proofs of formal logic, then the foundations of justice appear arbitrary. Rejecting both the coldness of positivism and the radical skepticism of thinkers like Jean-Paul Sartre, Perelman sought a middle path.

Collaborating with Lucie Olbrechts-Tyteca, Perelman turned to the Greco-Latin rhetorical tradition, specifically Aristotle’s distinction between demonstrative logic and dialectical reasoning. In their 1958 masterpiece, Traité de l'argumentation: la nouvelle rhétorique, they argued that philosophy is not merely about revealing absolute truths, but about persuading specific audiences. They proposed a 'regressive philosophy' that acknowledges how groups adhere to opinions with varying intensity, grounding reason in the probabilities of social life rather than the self-evident axioms of metaphysics.

Central to this 'new rhetoric' is the concept of the audience. Perelman argued that an orator must tailor their approach to both particular and universal audiences—the latter being an ideal construct of reasonable people. While critics like Jürgen Habermas and Henry Johnstone Jr. have questioned the practicality of this universal audience, arguing it lacks historical context or structure, Perelman maintained it serves as a necessary moral constraint. By emphasizing values and 'presence'—the rhetorical technique of making distant or abstract ideas feel immediate—Perelman provided a framework for how we construct truth in a world where clear, distinct ideas are rare.

Perelman’s influence extends far beyond philosophy, impacting fields from law to political geography. A recipient of the Francqui Prize and a member of the Belgian baronage, he remained a committed intellectual until his death in 1984. His work reminds us that even when we lack absolute certainty, we can still build reasonable, persuasive arguments that guide human action and foster a sense of communion.

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