Eduard Gottlob Zeller was a German philosopher and Protestant theologian of the Tübingen School of theology. He was well known for his writings on Ancient Greek philosophy, especially Pre-Socratic Philosophy, and most of all for his celebrated, multi-volume historical treatise The Philosophy of Greeks in their Historical Development (1844–52). Zeller was also a central figure in the revival of neo-Kantianism.

Ferdinand Christian Baur was a German Protestant theologian and founder and leader of the (new) Tübingen School of theology. Following Hegel's theory of dialectic, Baur argued that second century Christianity represented the synthesis of two opposing theses: Jewish Christianity and Gentile Christianity. This and the rest of Baur's work had a profound impact upon higher criticism of biblical and related texts.