Abstract
The two important factors in science development are the social economy (gross domestic product, GDP) and freedom. In order to follow the development of science for both old Arabic-Islamic and Western civilizations, a statistical method is used to trace the variation of scientists' population with time. The analysis shows that: 1- There is a growth in Arabic-Islamic sciences for a period of three centuries (AD 700-1000). Then it is followed by period of declination. The decay time is about of eight centuries. Major factor behind that decay in science activities and the block of the science thoughts may be attributed to religious thoughts domination, and cultural or thoughtful problems, in addition to the normal social problems like wars, disasters..etc. 2- The growth in western civilization started approximately in AD 1200 and remains in its growing. It looks that the wars, political problems have no serious effect in western sciences growth. The growth behaviour has a natural growth form. That may prove that, the secular society is quite perfect for such activities. For present time Arab-Islam societies have no distinguished contributions. The most important factor for that catastrophic retardation is the absence of the freedom of thought and believes. The obtaned curve has similarities with world GDP curve.