Roger Bacon, a 13th-century English Franciscan friar, is credited with strongly advocating empirical and experimental approaches to the study of nature. He argued that claims should be checked against sensory evidence, instruments, and trustworthy observation rather than accepted solely because an authority had stated them.
Bacon lived roughly from 1219 or 1220 to 1292 and studied at Oxford and Paris. His major work, the Opus Majus, was written in the 1260s for Pope Clement IV and discussed subjects including optics, mathematics, language, and natural philosophy. He emphasized experimentation as a way to discover what reason and books alone could not establish.
His work was connected to earlier traditions. Bacon drew on the optical writings of Ibn al-Haytham, known in Latin Europe as Alhazen, and was influenced by the English scholar Robert Grosseteste. The modern scientific method did not yet exist as a standardized procedure, so calling Bacon its inventor would be anachronistic.
A common mix-up is with Francis Bacon, the English philosopher who published Novum Organum in 1620. Roger Bacon was a medieval Franciscan; Francis Bacon lived centuries later. Roger Bacon's reputation as a solitary modern scientist is also overstated: much of his knowledge came from texts, and historians debate how many experiments he personally performed.