INTRODUCTION Mary Douglas
George Kelly's essay deals critically with methodological problems. He uses grid/group analysis to interpret the role of the philosophers Voltaire, Montesquieu and Diderot in eighteenth-century France. He specially considers the traps and ambiguities that lie in the approach as formulated now for the historian who tries to use it. His essay might well belong in the first section on method. We have placed him at the head of the section on comparative studies in history since he uses his deep familiarity with enlightenment thought and with the biographies of the thinkers to test just how far this historical material supports the claims made for grid/group analysis. He ends with questions that seem to be answerable with the same caveats which have been applied to the same problems raised by all the writers on method. What counts as a group, for example? It is difficult to say how much more of a distinctive group the philosophers were than the aristocrats or other categories. Disarmingly, George Kelly says that perhaps eighty years is too big a spread of time and that the allegiances would crystallize more clearly in a micro-study. But I do not think so. He is working over a time span similar to that of Martin Rudwick's essay. The latter is able to discern geological styles through the nineteenth century. The difference is that George Kelly in tracing the growth and maturity of a particular movement is inevitably aware of rough edges and curious adhesions to his definition of the subject. Martin Rudwick has a field already defined by the subject of geology and within it he identifies particular cognitive styles.