Muhammad ibn Zakariyā Rāzī (Mohammad-e Zakariā-ye Rāzi), known as Rhazes or Rasis after medieval Latinists (August 26, 865 – 925), was a Persian polymath, a prominent figure in Islamic Golden Age, physician, alchemist and chemist, philosopher, and scholar.
Numerous "firsts" in medical research, clinical care, and chemistry are attributed to him, including being the first to differentiate smallpox from measles, and the discovery of numerous compounds and chemicals including kerosene, among others. Edward Granville Browne considers him as "probably the greatest and most original of all the physicians, and one of the most prolific as an author".
Razi made fundamental and enduring contributions to the fields of medicine, alchemy, music, and philosophy, recorded in over 200 books and articles in various fields of science. He was well-versed in Ancient Persian, Greek and Ancient Indian medical knowledge and made numerous advances in medicine through own observations and discoveries.
Educated in music, mathematics, philosophy, and metaphysics, he chose medicine as his professional field. As a physician, he was an early proponent of experimental medicine and has been described as the father of pediatrics. He was also a pioneer of ophthalmology. He was among the first to use Humoralism to distinguish one contagious disease from another. In particular, Razi was the first physician to distinguish smallpox and measles through his clinical characterization of the two diseases. He became chief physician of Rey and Baghdad hospitals.
As an alchemist, Razi is known for his study of sulfuric acid.
According to Abu Hatim, Razi offered harsh criticism concerning religions, in particular those religions that claim to have been revealed by prophetic experiences. Razi asserted that "[God] should not set some individuals over others, and there should be between them neither rivalry nor disagreement which would bring them to perdition." He argued,
"On what ground do you deem it necessary that God should single out certain individuals [by giving them prophecy], that he should set them up above other people, that he should appoint them to be the people's guides, and make people dependent upon them?"
Concerning the link between violence and religion, Razi expressed that God must have known, considering the many disagreements between different religions, that "there would be a universal disaster and they would perish in the mutual hostilities and fighting. Indeed, many people have perished in this way, as we can see."
He was also critical of the lack of interest among religious adherents in the rational analysis of their beliefs, and the violent reaction which takes its place:
"If the people of this religion are asked about the proof for the soundness of their religion, they flare up, get angry and spill the blood of whoever confronts them with this question. They forbid rational speculation, and strive to kill their adversaries. This is why truth became thoroughly silenced and concealed."
Al-Razi believed that common people had originally been duped into belief by religious authority figures and by the status quo. He believed that these authority figures were able to continually deceive the common people "as a result of [religious people] being long accustomed to their religious denomination, as days passed and it became a habit. Because they were deluded by the beards of the goats, who sit in ranks in their councils, straining their throats in recounting lies, senseless myths and "so-and-so told us in the name of so-and-so..."
1.) Jennifer Michael Hecht, "Doubt: A History: The Great Doubters and Their Legacy of Innovation from Socrates and Jesus to Thomas Jefferson and Emily Dickinson", pg. 227-230
2.) Sarah Stroumsa (1999). Freethinkers of Medieval Islam: Ibn Al-Rawandi, Abu Bakr Al-Razi and Their Impact on Islamic Thought. Brill.
3.) Jennifer Michael Hecht, "Doubt: A History: The Great Doubters and Their Legacy of Innovation from Socrates and Jesus to Thomas Jefferson and Emily Dickinson", pg. 227-230