John Pecham c. 1230 – 1292

John Pecham was an English Franciscan friar, scholastic theologian, and natural philosopher, and from 1279 archbishop of Canterbury. After studies at Paris and Oxford and a long teaching career as a Franciscan master, he produced his influential Perspectiva Communis, a textbook of geometrical optics that synthesized the work of Alhazen, Roger Bacon, and earlier Western writers and remained a standard introduction to the science of vision into the seventeenth century. As archbishop he defended an Augustinian-Bonaventurean theology of divine illumination against the rising Aristotelianism associated with Thomas Aquinas, condemning a list of Thomistic propositions at Oxford in 1284.

John Pecham was born around 1230 in Sussex, was educated by the Cluniac monks of Lewes Priory, and studied liberal arts at Paris before entering the Franciscan Order around 1250. After theological studies at Paris and Oxford he became regent master in theology at Paris in 1269 or 1270, where he stood publicly against Thomas Aquinas in the disputation on the unicity of substantial form, and the same year took the Franciscan chair at Oxford. He served as provincial minister of England, lecturer at the papal Curia under Nicholas III, and from 1279 until his death in 1292 as archbishop of Canterbury.

His Latin works include the Tractatus de Anima, the Quaestiones de Beatitudine, the Quaestio de Aeternitate Mundi, several quodlibetal sets, the Defensio fratrum mendicantium against the secular masters, the Tractatus Pauperis on evangelical poverty, the Latin religious poem Philomena praevia, the Tractatus de Sphaera, and the very widely read optical textbook Perspectiva communis.

Pecham was the leading Augustinian Franciscan opponent of the new Aristotelianism, defending illumination, the plurality of substantial forms, and the active intellect as God; as archbishop he renewed in 1284 the Oxford condemnations of Thomistic theses first issued by his predecessor Kilwardby. His Perspectiva communis transmitted Alhacen's optics to the Latin West and was a standard university textbook for three centuries. He died at Mortlake in December 1292.