Sergio Sismondo's “Boundary Work and the Science Wars” nicely exemplifies a hotly debated central issue. One side, let me call them the rationalists, tries to explain episodes in the history of science in terms of reason. They claim that scientists, past and present, believe what they do because of the evidence that they have at the time. The other side, following Sismondo, let me call them STSers , claim that social and other non-cognitive factors are the frequent causes of belief. (...) This disagreement naturally leads to a meta-level debate. Rationalists, such as myself, try to give reasons for believing the STSers are wrong-headed in their approach. And Sismondo replies with the claim that whether I realize it or not I am really doing boundary work – an explanation of my activity in terms of social factors. (shrink)