In understanding styles of political judgement in government decision-making, explanatory limitations of rational choice, prospect theoretic, historical institutional, groupthink, and other approaches suggest that there is space for developing other frameworks. This article argues that the neo-Durkheimian institutional theoretical framework deserves serious consideration. It shows that it offers a powerful causally explanatory framework for generating theories of decision-making in government which can be examined using historical comparative research designs. The value of the concept of a ‘thought style’ for understanding political judgement is demonstrated, and contrasted sharply with ideology. The theory argues that informal institutions explain thought styles. Well-known cases from the Cuban missile crisis, and the Wilson and Heath governments illustrate the argument. The article rebuts criticisms offered of the neo-Durkheimian institutional framework in the literature. Finally, it identifies recent developments and innovations in the approach that make it especially suited to explaining political judgement in government decision-making.