May 2016 - Once people have seen that something happens through observation, sooner or later it will occur to them to ask why it happens, and whether there is any way of proving that it will happen the same way every time. Sumerians developed advanced math to predict the movements of the planets, and Thales figured out how to predict a solar eclipse. The Egyptians, according to Herodotus, used experiments to see what would happen in a certain situation. For instance, he reports that the Pharaoh wanted to find out what the first language on earth was, and so he ordered two babies to be put in a house alone, and the slaves who took care of them should not speak at all, to see what they would say first.
In the 500s BC, the Greek philosopher Pythagoras was interested in proving that things had to be true all the time, rather than just observing that they were true most of the time. Socrates began to develop a way of thinking and speaking which would let you prove that a certain statement was or was not true, which we call logic. Socrates' student Plato continued this idea, and Plato's student Aristotle began the process of applying this logic to the natural world.
In the Hellenistic period, many Greek, African, and West Asian scientists like Euclid and Aristarchus used Aristotle's logical system to investigate mathematics, biology, and medicine. These studies took place especially in the great Library at Alexandria in Egypt. These scientists kept on working after the Romans took over ruling Greece and Egypt. An African scientist named Ptolemy did careful experiments to figure out how people's eyes worked.
After the Islamic Empire was established in the late 600s AD, scientific research took off again. In physics, Ibn Sina figured out the basic natural laws governing motion and momentum in the 900s AD. In the 1100s AD, Maimonides realized that people got sick from bad water and air (though he didn't know about germs), rather than from magic spells or curses. Ibn Rushd, at the same time, tried to use logic to figure out the nature of the soul.
By the 1100s AD, Europe was for the first time becoming a center for scientific thought. Monks, in the role of professors, were teaching Socratic logic to students in the monastic schools and cathedral schools (the beginnings of modern universities) at Paris and Cambridge and Oxford. Men like Peter Abelard tried to use logic to prove the existence of God, and to define His nature. At the ducal court of Aquitaine, Eleanor of Aquitaine and her court used the same logical principles to discuss the nature of love.
By the 1200s, Islamic and European scholars talked to each other more. Thomas Aquinas and Roger Bacon imitated the work of Maimonides, Ibn Sina and Ibn Rushd to build a more logical version of Christianity. In the next century - the 1300s AD - Ibn Khaldun in North Africa applied logical principles to the study of history and economics, breaking new ground.