This paper examines how critical thinking is perceived and transmitted in higher education (HE) classrooms using two Vietnamese undergraduate programmes as case studies. The analysis of semi-structured interviews with teachers, supervisors and institutional leaders from both programmes reveals transmission of critical thinking is impacted upon by power relations from not only outside, in the form of cultural and political ideologies, but also "within" the pedagogic discourse itself. Guided by Bernstein's concepts of the pedagogic device, classification and framing, the discussion centres on how organisational and pedagogic decisions on critical thinking prepare Vietnamese students to think, or not, 'the unthinkable'. While teachers cannot unilaterally alter official curriculum texts to make critical thinking accessible to all students, it is the former's engagement, or not, in the re-organisation of curricular texts, and the use of particular pedagogic practices that can bring about change.