arbitrium

Arbitrium is a Latin noun meaning discretion, judgment, will, or choice. It derives from the verb arbiter, a judge or mediator, and in Latin usage it often denotes the power to decide according to one’s own judgment rather than by strict rule. In English academic usage the term appears mainly in discussions of authority, moral philosophy, and classical legal language, and the related adjective form is arbitral or discretionary.

In classical and late antique contexts, arbitrium commonly referred to the discretionary power of a person in authority—such as a magistrate or judge—to decide, temper, or modify a decision within the broad bounds of law or custom. The term can convey both mercy and leniency granted at the discretion of an official, as well as the personal act of deciding a matter.

In theology and philosophy, the phrase liberum arbitrium — literally “free will” — is central to debates about human freedom and responsibility. Augustine, and later medieval theologians, used the term to discuss whether humans can freely choose good or evil and how divine grace interacts with human choice. The concept influenced discussions on predestination, grace, and moral accountability in Christian thought.

In modern usage, arbitrium survives mainly in historical or doctrinal texts and in the related notion of arbitral discretion within legal or administrative contexts. It also underpins the English word arbitration, through the same Latin root referring to the act of voluntary, deliberative decision or settlement by an arbiter.