This chapter traces the development of dialectical reasoning from the Middle Ages to the Renaissance, highlighting significant shifts in its status, function, and scope. In the medieval period, dialectic was at the centre of intense intellectual conflict between ‘dialecticians’ and ‘anti-dialecticians’, particularly concerning its legitimacy in matters of faith and theology.Within the scholastic tradition, dialectic became a foundational method for constructing logical arguments and promoting rigorous intellectual inquiry. These debates culminated in the realist–nominalist controversy, which raised fundamental ontological questions about the status of universals and their relationship to particular entities. The Renaissance marked a decisive transformation in the role of dialectic, as it underwent a radical reappraisal by key thinkers seeking to break with the constraints of Scholastic orthodoxy. Nicholas of Cusa introduced the concept of coincidentia oppositorum, extending dialectic beyond the confines of traditional Aristotelian logic. Meanwhile, Giordano Bruno emphasised the infinite nature of the universe, challenging the geocentric and finite cosmologies that had long dominated medieval thought.