Proceeding from the assumption that 'how' we think about something (reflection and reasoning) has a decisive influence on 'what' we know about it, the study attempts a microanalytic reconstruction of the practical reasoning potential of participants in conversations. There is major focus on three areas: 1. standard situations in everyday communication (e.g. greeting sequences, mother-child interaction); 2. communication in class (teaching grammar, role-play); 3. East-West communication (conference exchanges, talk-shows). The conclusion the author comes to is that, as a product of heterogeneous forms of reasoning and reflection, the language awareness of speakers deviates from established linguistic insights about language in a way which is not random but systematic.