Muslim scientists placed a greater emphasis on experimentation than previous ancient civilizations (for example, Greek philosophy placed a greater emphasis on rationality rather than empiricism), which was due to the emphasis on empirical observation found in the Qur’an and Sunnah, and the rigorous historical methods established in the science of hadith. Muslim scientists thus combined precise observation, controlled experiment and careful records with a new approach to scientific inquiry which led to the development of the scientific method in particular. In particular, the empirical observations and experiments of Ibn al-Haytham (Alhacen) in his Book of Optics (1021) are seen as the beginning of the modern scientist method, which he first introduced to optics and psychology. Rosanna Gorini writes:

“According to the majority of the historians al-Haytham was the pioneer of the modern scientific method. With his book he changed the meaning of the term optics and established experiments as the norm of proof in the field. His investigations are based not on abstract theories, but on experiment evidences and his experiments were systematic and repeatable.”

Other early experimental methods were developed by Geber (for chemistry), Muhammad al-Bukhari (for history and the science of hadith), and al-Kindi (for the Earth science), Avicenna (for medicine), Abu Rayhan al-Biruni (for astronomy and medicine), Ibn Zuhr (for surgery) and Ibn Khaldun (for the social sciences). The most important development of the scientific method, the use of experimentation and quantification to distinguish between competing scientific theories set within a generally empirical orientation, was introduced by Muslim scientists.

Ibn al-Haytham, a pioneer of modern optics, used the scientific method to obtain the results in his Book of Optics. In particular, he combined observations, experiments and rational arguments to show that his modern intromission theory of vision, where rays of light are emitted from objects rather than from the eyes, is scientifically correct, and that the ancient emission theory of vision supported by Ptolemy and Euclid (where the eyes emit rays of light), and the ancient intromission theory supported by Aristotle (where objects emit physical particles to the eyes), were both wrong. It is known that Roger Bacon was familiar with Ibn al-Haytham’s work.

Ibn al-Haytham developed rigorous experimental methods of controlled scientific testing in order to verify theoretical hypotheses and substantiate inductive conjectures, Ibn al-Haytham’s scientific method was similar to the modern scientific method in that it consisted of the following procedures:

1. Observation


2. Statement of problem


3. Formulation of hypothesis


4. Testing of hypothesis using experimentation


5. Analysis of experimental results


6. Interpretation of data and formulation of conclusion


7. Publication of findings