Girolamo Saccheri

…Logic”) of the Italian Jesuit Gerolamo Saccheri. Saccheri is better known for his suggestion of the possibility of a non-Euclidean geometry in Euclides ab Omni Naevo Vindicatus (1733; “Euclid Cleared of Every Flaw”). Another incisive traditional logic was that of the Dutch philosopher Arnold Geulincx, Logica fundamentis suis restituta (1662;…

In 1733 the Italian Girolamo Saccheri published his Euclides ab Omni Naevo Vindicatus (“Euclid Cleared of Every Flaw”). This was an important work of synthesis in which he provided a complete analysis of the problem of parallels in terms of Omar Khayyam’s quadrilateral (see the figure). Using the Euclidean…

In 1733 Girolamo Saccheri (1667–1733), a Jesuit professor of mathematics at the University of Pavia, Italy, substantially advanced the age-old discussion by setting forth the alternatives in great clarity and detail before declaring that he had “cleared Euclid of every defect” (Euclides ab Omni Naevo Vindicatus, 1733).…