“There is a kind of increase in complexity through chemistry and biology, until you get to the social sciences, which are about as complex as you can get. There, research is completely different. A theory in social science is not at all the same as a theory in science. It’s psychology – you have to take into account peoples’ way of thinking. Of course it’s called social science because one tries to apply scientific reasoning. But for me, many of the theories in social science, and indeed in science education, seem more like perspectives. You interpret your data from one perspective and even design your study from that perspective. However, someone else could come along and see the same thing from a very different angle. So you can have several different theories running in parallel and it’s very hard to see the development. It’s very difficult to prove that one theory is better than another because it’s all so complex. This is something we natural scientists have to get used to – and I think we have been criticising each other far too often.