 Different authors assume different stances in this debate, and we will discuss their positions below. However, there are few, if any, thoroughgoing universalists and so a review like the current one has to discuss different cases. Unfortunately space constraints prevent us from examining all the different varieties of scientific/epistemic representation, and a selection has to be made. This invariably leads to the neglect of some kinds of representations, and the best we can do about this is to be explicit about our choices. We resolve to concentrate on scientific models, and therefore replace our variable \(S\) for the object doing the representing with the variable \(M\) for model. This is in line both with the more recent literature on scientific representation, which is predominantly concerned with scientific models, and with the prime importance that current philosophy of science attaches to models (see the SEP entry on  models in science  for a  survey).[6]