Philosophy of social science (PoS) typologies can help practitioners in the social sciences to reflect upon the often-tacit assumptions embedded in research. Existing PoS typologies however suffer from various shortcomings, one of them being a tendency to present extreme versions of the assumptions underpinning research. Having considered this and other shortcomings, the present paper advances a flexible PoS typology. Operating with strong and moderated versions of three PoS perspectives – positivism, constructionism and (critical) realism – the typology captures key assumptions underpinning a broad range of contemporary social research. Moreover, it opens up the possibility of contemplating the assumptions embedded in research in a more fruitful way. To render tangible how the typology constitutes an improvement over existing typologies, it is used in reflections on sustainability research on climate negotiations, green growth and housing development.