 Rather than acting as a substitute, the effective and responsible use of artificial intelligence tools in big data analysis requires the strategic exercise of human intelligence—but for this to happen, AI systems applied to big data need to be accessible to scrutiny and modification. Whether or not this is the case, and who is best qualified to exercise such scrutiny, is under dispute. Thomas Nickles argued that the increasingly complex and distributed algorithms used for data analysis follow in the footsteps of long-standing scientific attempts to transcend the limits of human cognition. The resulting epistemic systems may no longer be intelligible to humans: an “alien intelligence” within which “human abilities are no longer the ultimate criteria of epistemic success” (Nickles forthcoming). Such unbound cognition holds the promise of enabling powerful inferential reasoning from previously unimaginable volumes of data. The difficulties in contextualising and scrutinising such reasoning, however, sheds doubt on the reliability of the results. It is not only machine learning algorithms that are becoming increasingly inaccessible to evaluation: beyond the complexities of programming code, computational data analysis requires a whole ecosystem of classifications, models, networks and inference tools which typically have different histories and purposes, and whose relation to each other—and effects when they are used together—are far from understood and may well be untraceable.