This article contrasts the opposing views of two of the Spanish late scholastics concerning the determinants of the “just price.” Cristóbal de Villalón (Provechoso tratado de cambios, 1542) puts forth a labor theory of value and argues for state intervention as a means of attaining justice in financial transactions. Saravia de la Calle reacts to Villalón’s position (Intrución de mercaderes, 1544). He puts forth a utility theory of value and argues that market forces, not costs, are the determinants of the just price. He further maintains that attempts to fix prices are fundamentally unjust—even if sanctioned by the state. By using logic, common sense, and empirical observation he demolishes Villalón’s antimarket position. The existence of these contrasting views demonstrates the opposition of market liberalism and antiliberalism at the early stages of the modern market economy.