"The early Islamic ages were a golden age for knowledge, and the history of the scientific method must pay a great deal of respect to some of the brilliant Muslim philosophers of Baghdad and Al-Andalus.

They preserved the knowledge of the Ancient Greeks, including Aristotle, but also added to it, and were the catalyst for the formation of a scientific method recognizable to modern scientists and philosophers.

The first, and possibly greatest Islamic scholar, was Ibn al-Haytham, best known for his wonderful work on light and vision, called 'The Book of Optics.' He developed a scientific method very similar to our own:

(1) State an explicit problem, based upon observation and experimentation.
(2) Test or criticize a hypothesis through experimentation.
(3) Interpret the data and come to a conclusion, ideally using mathematics.
(4) Publish the findings

Ibn al-Haytham, brilliantly, understood that controlled and systematic experimentation and measurement were essential to discovering new knowledge, built upon existing knowledge.

His other additions were the idea that science is a quest for ultimate truth and that one of the only ways to reach that goal was through skepticism and questioning everything.

Other Muslim scholars further contributed to this scientific method, refining it and preserving it. Al-Biruni understood that measuring instruments and human observers were prone to error and bias, so proposed that experiments needed replication, many times, before a 'common sense' average was possible.

Al-Rahwi (851 - 934) was the first scholar to use a recognizable peer review process.

In his book, Ethics of the Physician, he developed peer review process to ensure that physicians documented their procedures and lay them open for scrutiny. Other physicians would review the processes and make a decision in cases of suspected malpractice.

Abu Jābir, known as Geber (721 - 815), an Islamic scientist often referred to as the father of chemistry, was the first scholar to introduce controlled experiments, and dragged alchemy away from the world of superstition into one of empirical measurement.

Ibn Sina (Avicenna), one of the titans in the history of science, proposed that there were two ways of arriving at the first principles of science, through induction and experimentation. Only through these methods could the first principles needed for deduction be discovered

Other Islamic scholars contributed the idea of consensus in science as a means of filtering out fringe science and allowing open reviews. These contributions to the scientific method, and to the tools required to follow them, made this into an Islamic Golden Age of science.

However, with the decline in the Islamic Houses of Knowledge, the history of the scientific method passed into Europe and the Renaissance."
By Martyn Shuttleworth
<explorable.com/history-of-the-scientific-method>

...

Notable mention: "Abu Bakr Mohammed ibn Zakariya al-Razi, known in the West as Rhazes, was born in al-Rayy outside Tehran. He is considered one of the greatest physicians Islam has ever produced. He traveled widely, visiting famous medical centers of his time in Jerusalem, Cairo, and Cordova. In 907 he was appointed director of a large hospital in Baghdad and a court physician as well. He wrote 237 books, of which 36 have survived. The most famous of his works is Liber Continens, a medical encyclopedia.

In his theories, al-Razi was a Galenist; in practice, he was guided more by the principles of Hippocrates (1). He was known for taking detailed histories from his patients and for his keen observational skills. al-Razi combined psychological methods and physiological explanations. He used psychotherapy in a primitive but dynamic fashion (2).

As the director of the hospital in Baghdad, he established a special section for the treatment of the mentally ill. He treated his patients with respect, care, and empathy. As part of discharge planning, each patient was given a sum of money to help with immediate needs. This was the first recorded reference to psychiatric aftercare and, perhaps, to the existence of a psychiatric consultation service in a general hospital.

al-Razi is also known for his contributions to psychiatric ethics. In his treatise “Upon the Circumstances Which Turn the Head of Most Men From the Reputable Physicians,” al-Razi set clear standards for the professional practice of physicians. He advised physicians on how to retain the respect and confidence of their patients. At the same time, he advised patients to evaluate their physicians and demand from them a high level of integrity. He further advised patients to avoid physicians who are actively addicted to wine, a clear recognition of the problem of physician impairment over 1,000 years ago. al-Razi's words on this subject are no less applicable today (3)." ~ AMIN N. DAGHESTANI, M.D.
<ajp.psychiatryonline.org/doi/full/10.1176/ajp.154.11.1602>

REFERENCES
1. Parke-Davis & Co: Rhazes and Arabic medicine, in Great Moments inMedicine. Stories by Bender GA; paintings by Thom RA. Detroit, North-wood Institute Press, 1966, pp 62–67
2. Alexander FG, Selesnik ST: The History of Psychiatry: An Evaluation ofPsychiatric Thought and Practice From Prehistoric Times to the Present.New York, Harper & Row, 1966, p 62
3. Gordon BL: Medieval and Renaissance Medicine. New York, Philosophical Library, 1959, pp 152–164

Images

(1) Ḥasan Ibn al-Haytham, Latinized as Alhazen (c. 965 – c. 1040)
Description: English: Cropped version of the frontispiece of Johannes Hevelius, Selenographia, depicting Ibn al-Haytham (Alhazen)
Date: 1647
Source: Johannes Hevelius, Selenographia
Author: Artwork drawn by Adolph Boÿ, engraved by Jeremias Falck
License: Public Domain, <commons.wikimedia.org/w/index.php?curid=68649076>

(2) Abū Rayhān al-Bīrūnī (973-1048)
Description: English: USSR stamp, Abū Rayhān al-Bīrūnī, 6 copecks, 1973.
Date: 3 April 2005 (original upload date)
Source: Originally from <sl.wikipedia>
Author: The original uploader was Romanm at Slovenian Wikipedia.
License: Public Domain, <commons.wikimedia.org/w/index.php?curid=2590841>

(3) Ishāq bin Ali al-Rohawi (851-934)
Description: Ishāq bin Ali al-Rohawi's "Adab al-Tabib" (English: "Ethics of the Physician" ) remains in print.
<bpadjogja.info/adab-al-tabib-88>
<goodreads.com/book/show/44417144-adab-al-tabib-al-ruhawi>

(4) Paper: "Religious Tradition of Ishāq bin Ali al-Rohawi"
Description: Modern day physicians continue to write about al-Rhohawi's "Adab al-Tabib"
<ishim.net/ishimj/5/03.pdf>

(5) Jābir ibn Ḥayyān (died c. 806−816)
Description: English: The alchemist Jabir ibn Hayyan, from a 15th century European portrait of Geber, Codici Ashburnhamiani 1166
Source: Codici Ashburnhamiani 1166, Biblioteca Medicea Laurenziana, Florence
Author: Codici Ashburnhamiani 1166, Biblioteca Medicea Laurenziana
Uploaded by: user Halfdan
Biblioteca Medicea Laurenziana, Florence
License: Public Domain, <commons.wikimedia.org/w/index.php?curid=163740>

(6) Abū Ali Sina, known in the West as Avicenna (980-1037)
Title: Français: Avicenne / Avicenna / Ibn Sina (980-1037)
Description: Depicted person: AVICENNE / AVICENNA / IBN SINA
Accession Number: Banque d'images de la Bibliothèque interuniversitaire de santé : CIPB2067
This document belongs to the collections of the Bibliothèque interuniversitaire de santé. It was uploaded to Commons through a partnership with Wikimedia France.
License: Licence Ouverte, <commons.wikimedia.org/w/index.php?curid=60257575>

(7) Abū Bakr Muhammad Zakariyyā Rāzī, Latinized Rhazes or Rasis (AD 865 - 925)
Title: Portrait of Rhazes (al-Razi) (AD 865 - 925)
Description: Portrait of Rhazes (al-Razi) (AD 865 - 925), physician and alchemist who lived in Baghdad
References: Photo number: L0005053
Source: <wellcomecollection.org/works?wellcomeImagesUrl=/indexplus/obf_images/40/fd/f7548c12356bc6802be29b9a5fba.jpg>
License: CC-BY-4.0, CC BY 4.0, < commons.wikimedia.org/w/index.php?curid=66479542>