While big data is ubiquitous these days, there seems to be a lack of agreement about what it is and how it has affected and will continue to affect the political sciences. While most of the debate on big data focuses on its innovations in terms of the data itself—often using the 5 V’s of volume, velocity, variety, veracity and value—I argue that its real innovation lies in its ruthless promotion of dataism: the belief that data, and only data, should be at the heart of all research. And while this highly empirical view has already produced interesting and often revolutionary insights, it leaves little room for a more qualitative and holistic view of society. Here, I will discuss the world-view at the heart of dataism, the implications of dataism for political methodology, and the ethical problems big data can raise. I will conclude with some reflections on its implications for the field of political science in Europe.