(1527-1580) was a Spanish theologian born in Medina de Rioseco, Spain.
Medina studied theology at the University of Salamanca under the celebrated professor Francisco de Vitoria.
His life was devoted almost entirely to teaching theology at Salamanca, first in the chair of Durandus, afterwards as principal professor.
He was appointed to the "cathedra primaria" after a successful concursus, in public, against the learned Augustinian scholar Juan de Guevara (1518-1600).
Medina's probabilist doctrine consisted of the contention that if two opinions are probable in unequal degree, the less probable may be followed (Si est opinio probabilis, licitum est eam sequi, licet opposita probabilior sit); in moral theology, the consequence of probabilism is that if the licitness of an action is in doubt, it is lawful to choose a probable opinion favouring liberty rather than a more probable opinion favouring the law.