Meta Ontology

First of all, this paper aims at a clarification of Wittgenstein's conception of grammatical propositions. Their essential characteristics will be developed and some of the central questions concerning their status will be discussed: Should grammatical propositions be seen as arbitrary conventions? How do they work in practices? And how do they relate to natural facts? Later on, the two propositions "Every rod has a length" and "Sensations are private" will be discussed in more detail, for both fulfil three important features of grammatical propositions: They are not empirical descriptions, they are rules of a practice, and they are not knowledge-claims but express insights. Focussing on the grammar of pain language, it will be shown what kind of interdependency exists between grammar and natural facts. It will also turn out that some grammatical propositions are closely connected to our understanding of living a human form of life.