This is the last of a four part series on Ibn Khaldun (1332-1406), the African Arab intellectual widely considered to be the founder of sociology and the philosophy of history. We will be reading from the introduction of his Muqaddimah ("Prolegomena"), and discussing his insights on historical methodology, some epistemological problems they raise, and their continued relevance in contemporary life. In part four, we examine Ibn Khaldun’s elaboration on why the historian must be aware of the significance of changes in cultural conditions over time, culminating in his statement that, when such changes occur, it is ‘as if the whole world changes.’ This leaves us, again, with the question of whether the scientific history Ibn Khaldun aspires to requires a vantage point immune to such change, and whether (and how) that is possible.