 He argued, for example, that the categories of space and time were not "a priori".Rather, the category of space depends on a society's social grouping and geographical use of space, and a group's social rhythm that determines our understanding of time.In this Durkheim sought to combine elements of rationalism and empiricism, arguing that certain aspects of logical thought common to all humans did exist, but that they were products of collective life (thus contradicting the tabula rasa empiricist understanding whereby categories are acquired by individual experience alone), and that they were not universal "a priori" truths (as Kant argued) since the content of the categories differed from society to society.