(ProQuest: ... denotes formula omitted.)The historiographical entity we traditionally call most cases is taken for granted and more-or-less considered as unproblematic. On a closer look, however, it becomes a notoriously difficult and elusive subject. This is the reason for putting the term quotation marks. The difficulty and elusiveness manifests itself on many levels, and it is only a first problem that the term itself is problematic from chronological and geographical aspects.In what follows I will argue that is not something given, and that many historical approaches commonly adopted when writing about are seriously flawed because of unjustified hidden assumptions. In the end I will plead for the validity of the original insight of Harry A. Wolfson (1887-1974), who claimed that the religious character is the distinctive mark of philosophy. I will try to illustrate this point by analyzing the specific problem of theology as a science, which is a prerequisite for understanding the peculiar character of the philosophical enterprise.First I will try to state the simplest cases for the complexity of philosophy. As it is well known, there are intricate reasons explaining the difficulties of the subject.' The first problem applies to the term medieval. Originally a disparaging term coined by gentleman scholars with the high political aim of re-establishing the glory of Rome, it was meant to describe the period between the fall and the expected restoration of the Empire. All this sounds familiar. However the political history clearly runs independently of the history of intellectual trends. First of all, very few Renaissance scholars wanted to re-establish the religion of ancient Rome (to be sure, there were some notable exceptions favoring pristine Greek or ancient Egyptian religion, but they remained a minority).In a different sense no intermediacy, no time can be applied either to Byzantium (since there was no discontinuity between ancient Rome and Byzantium for the rhomaioi of the empire), or to Islam (which was still its first phase, addition to completely lacking terms for being in between). The same applies a fortiori to Jewish philosophy.On the other hand, all the three branches of medieval did share a common heritage science (since the term philosophy this period was practically equivalent to what the modern era calls science). For starting points the various philosophical disciplines, all three (or four) branches, like Latin Christian, Byzantine Christian, Arabic or Persian Muslim, or Jewish intellectuals, looked to Aristotle for logic, psychology, and metaphysics; Euclid for geometry; Ptolemy for astronomy; Galen for medicine; Plotinus for scientific theology; and to the Hellenistic commentators (or to the Neo-Platonists) for guidance the maze of profound and arcane problems constituting their joint heirloom.The differences between the Jewish, Christian (in its Latin, Byzantine, or Syriac branches), and Islamic thinkers the united realm of Hellenistic learning (allowing for differences the pace and depth the acquisition of this learning, and for ongoing mutual influences and challenges) resulted from their different theological assumptions, that is, from their different creeds. It was their different creeds that affected, the form of a kind of backward causation, the scientific (philo-sophical) principles that the thinkers of these religions accepted, rejected, or modified. Ar-guments were accepted or rejected against the respective theological principles, but other-wise the traffic went both ways. Not only were the arguments of Maimonides influential for (e.g.) Thomas Aquinas, but also those of Duns Scotus for Hasdai Crescas. Arabic largely came to an end toward the final years of the twelfth century, but the beginning it re-lied on the same Hellenistic philosophical inheritance as the other three branches. …