C. B. Macpherson has argued that modern liberalism has its roots in the possessive individualism and the conception of self-ownership of some English philosophers of the 17th century. But a conception of moral self-ownership began already to emerge in the scholastic discourse of conscience and moral decision making in the 16th century. In order to see this, a suitable and convincing concept of moral- self-ownership has first to be defined. This concept was present in scholastic probabilism around 1600 under the title of possessing one’s own freedom from moral restriction. The paper will investigate how far back this peculiar set of ideas can be traced.

My presentation will proceed as follows:
First, I will shortly explain the concept of moral self-ownership and why it makes sense to move from Macpherson to the scholastics (sec. 1). Then I will introduce a medieval principle of property law which favors actual possessors of goods in cases of disputed ownership (Sec. 2). Section 3 shows that this principle was applied in novel ways by the eminent Spanish theologian Domingo de Soto. Soto paved the way for the principle’s career as general rule of moral decision making under uncertainty in scholastic probabilism, which was invented by Bartolomé de Medina in 1577 (Section 4). Probabilism’s principle of moral self-ownership was later equated with a ius libertatis of acting at will in the boundaries of well established moral laws (Sec. 5).