This paper makes an independent start with formalizing the rules for the argumentation stage of critical discussions. It does not deal with the well-known code of conduct consisting of ten rules but with the system consisting of fifteen rules on which the code of conduct is based. The rules of this system are scrutinized and problems they raise are discussed. Then a formal dialectical system is defined that reflects most of the contents of these rules. The aim is to elucidate (...) the way the rules work and to show how a formal approach can be useful to achieve this. It is also shown how the present method can be used to study the nature of circular argumentation. While, generally, the formalization follows closely the original rules for the argumentation stage of critical discussions, there will also be proposed some modifications of the original protocol. (shrink)