  For Duhem there is a crucial difference between representing and explaining. He divides theories into two large categories, explanatory and purely representative theories, and argues that physical theories should not be considered as explanatory, but as purely representative or classificatory. The argument, as we have seen, is that, in order for physical theory to be explanatory, it would have to be subordinate to metaphysics and not autonomous. The reference to the two words having the same meaning for Maxwell and English scientists is thus a reference to what Duhem would consider a confusion about the aim of physical theory, one that arises in the identification of the model with the theory, in thinking that what is represented by the theory and/or model is real.