Within the ideal model of pragma-dialectics discussants act rationally and without any time limits. A rhetorical model of argumentation can be derived by including human restrictions. In this practical model (i.e. not ideal model) discussants have to resolve a difference of opinion within limited time, on the basis of incomplete information, in the awareness of their restricted rationality, and by means of a non-perfect language. They try to maximize their long-term success in persuading the audience under the given limitations. Rhetoric provides means for coping with these limitations by way of following a practically applied rationality.