This paper is part of my Ph.D. thesis in which I attempted to bring together cognitive and affective dimensions of mathematics teachers' practice, often considered separately. In particular, during my Ph.D. research, I tried to construct a theoretical framework for the study, first reviewing Habermas' theory of rationality and its criticism. Then, I extended this framework into the emotional sphere drawing both on the neuropsychological research and on the research on affect in mathematics education. Lastly, I used the new framework to analyse the rationality and emotionality of two mathematics teachers using data from interviews and classroom video recordings.