Science is the study of the physical world, but it is not just a topic, a subject, a field of interest. It is a discipline—a system of inquiry that adheres to a specific methodology—the scientific method. The heart of the scientific method is the use of verifiable experiments to test the validity of hypotheses. One can study phenomena without adhering to the scientific method, of course. The result, however, is not science. It is pseudoscience or junk science.
Throughout history, many people have studied nature without using the scientific method. Some of the earliest people to do so were the ancient Greeks. Scholars such as Aristotle made many observations about natural phenomena, but they did not test their ideas with experiments. Instead, they relied on logic to support their findings. As a result, they often arrived at erroneous conclusions. Centuries later, the errors of the Greeks were exposed by scholars using the scientific method.
Perhaps the most famous example of disproving a false idea with an experiment occurred in 1589 when Galileo Galilei challenged Aristotle’s notions about falling bodies. Galileo was not the first person to conduct experiments or to follow the scientific method, however. European scholars had been conducting experiments for three hundred years, ever since a British-born Franciscan monk named Roger Bacon advocated experimentation in the thirteenth century. One of Bacon’s books, Perspectiva (Optics) challenges ancient Greek ideas about vision and includes several experiments with light that include all the steps of the scientific method.
Bacon’s Perspectiva is not an original work, however. It is a summary of a much longer work entitled De aspectibus (The Optics). Perspectiva follows the organization of De aspectibus and repeats its experiments step by step, sometimes even word for word. But De aspectibus is not an original work, either. It is the translation of a book written in Arabic entitled Kitāb al-Manāzir (Book of Optics). Written around 1021, Kitāb al-Manāzir predates Roger Bacon’s summary of it by 250 years. The author of this groundbreaking book was a Muslim scholar named Abū ‘Alī al-Hasan ibn al-Hasan ibn al-Haytham.
Born in Basra (located in what is now Iraq) in 965, Ibn al-Haytham (known in the West as
Alhazen or Alhacen) wrote more than 200 books and treatises on a wide range of subjects. He was the first person to apply algebra to geometry, founding the branch mathematics known as analytic geometry.
Ibn al-Haytham’s use of experimentation was an outgrowth of his skeptical nature and his Muslim faith. He believed that human beings are flawed and only God is perfect. To discover the truth about nature, he reasoned, one had to allow the universe to speak for itself. “The seeker after truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them,” Ibn al-Haytham wrote in Doubts Concerning Ptolemy, “but rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration.”
To test his hypothesis that “lights and colors do not blend in the air,” for example, Ibn al-Haytham devised the world's first camera obscura, observed what happened when light rays intersected at its aperture, and recorded the results. This is just one of dozens of “true demonstrations,” or experiments, contained in Kitāb al-Manāzir.
By insisting on the use of verifiable experiments to test hypotheses, Ibn al-Haytham established a new system of inquiry—the scientific method—and earned a place in history as the world’s
first scientist.
