Among the various issues debated in philosophy today, this book focuses on one which is unquestionably central: can we claim to have any regulated procedure that uses common norms to resolve human disagreements? Although this is a question with profound classical roots, it is explored in this work through the prism of a key notion in today's thought: controversy. The aim of adopting this approach is to determine whether controversies might constitute this regulated procedure. What are controversies? Are they only a type of reasoned and ordered debate? Are they a complex process of making or fixing rational beliefs? Each chapter of this book can be seen as a way of contributing to the analysis of human rationality, but viewed not so much as something unitary and pre-established that needs to be discovered, but rather as something that is neither unitary or pre-established; something that still needs to be achieved.