Big data is the use of extremely large data sets that may be analysed computationally to reveal patterns, trends, and associations. Some of the more optimistic among us think that big data can be employed to craft better social policy thereby creating more functional and livable societies. I trace the origins of this techno optimism showing its roots in Auguste Comte's Postivism movement in the 19th century and the earlier dreams of the Enlightenment and hint at what may be lacking in such optimism.