Conventionalists

Conventionalists are proponents of conventionalism, a family of philosophical positions that holds that some fundamental statements in science, mathematics, and language are not determined by empirical facts alone but are true or false by convention, stipulation, or pragmatic choice. They argue that certain axioms, definitions, or methodological commitments are adopted because they are useful or coherent within a given framework, rather than because they mirror an objective reality.

Historically, conventionalist ideas emerged in the early 20th century with figures such as Henri Poincaré and Pierre Duhem, who emphasized the conventional character of scientific theorizing and the underdetermination of theory by data. Poincaré argued that geometry could be treated as a convention for organizing experience, while Duhem stressed that empirical tests confront networks of hypotheses rather than isolated propositions. In later decades, Ernst Mach and Hans Reichenbach extended conventionalist themes into the philosophy of science, including discussions of the conventionality of simultaneity and measurement. The movement also intersected with logical positivism, as philosophers explored how language, definitions, and theoretical choices function within scientific inquiry.

Conventionalists typically differentiate between empirical content and the conventions that frame interpretation, such as the choice of axioms or measurement protocols. Notable examples include the conventionality of geometry (how Euclidean versus non-Euclidean geometries are chosen based on convenience and empirical adequacy) and the Einstein synchronization convention used to define simultaneity in special relativity. The notion also appears in debates about the conventional aspects of scientific theory choice and language.

Critics argue that conventionalism can undermine objective knowledge or overemphasize contingency in scientific commitments. Defenders contend that acknowledging conventions clarifies how theories succeed and explains shifts in scientific perspective without denying empirical success.