The article makes three types of arguments to support the claim that it is necessary to emphasise international theory in teaching (and researching) International Relations. The first argument is logical: no empirical analysis is without theoretical assumptions. There is no explanation, which is simply a neutral selection of "data speaking to us". For social science theories are not only the result of knowledge, but also the condition for the very possibility of knowledge. The second argument is educational: training future practitioners and observers to track underlying assumptions in empirical argument fulfils the crucial role of a more time-independent intellectual education. Besides the necessary factual training, they need to acquire i...