 Hi, this unit shows how sentence meaning can be formally defined by means of truth conditional semantics. It introduces the notion of simple and complex propositions to define sentence meaning and explains how propositions can be related in terms of entailment and presupposition. In the virtual session which contains two e-lectures and several micro lectures, we will first define problems with words and will then define the principles of propositional logic first by means of simple and then on the basis of complex propositions. As a result, we will define entailment and several logical relations between propositions. If you need help on how to proceed, use the question sheet with its hyperlinks and its video links for guidance. The mastery worksheet is a dynamic multiple choice task about propositional logic. Please work through the virtual session first before tackling this worksheet. Well, and the practical provides you with many sentences ready for propositional analysis. Please make use of this data in order to understand how sentence meaning can be expressed formally.