In the decade after 1945 Artificial Intelligence and connectionistic ideas were not separated. The term "Artificial Intelligence" was not even born at that time. One of the aims at that time was to understand the working of the human brain and to describe the process of thinking in a formal and mathematical way. Different aspects came together and evolved into what researchers like Norbert Wiener called cybernetics. It was based on a long history and contained important ingredients from mathematical logic as well as from statistical mechanics. In the following we will isolate three periods in an attempt to structure human science. The connectionistic paradigm denotes in this light a new and fourth historical period.