In the guild of economic historians there is a lively group that claims original ideas about the economic situation during the later Middle Ages. Because of the dark tones of their historical descriptions, I think one may refer to them as 'stagnationists'. There was in a recent issue of the Economic History Review a bold sketch of the growth of the sect and a general summary of the state of the stagnationist belief. 1 The general tone of this manifesto is undoubtedly that of self complacency and satisfaction. 'The champions of reaction', writes Professor R. S. Lopez, are fighting 'a spirited rearguard action' but 'it does not seem likely at present that they will turn the tide in economic history'. The economic historians who do not share the views of the sect are banned as discredited people. As for the 'intellectual and art historians', Professor Lopez declares that he is 'the last to blame them for their occasional retard in catching up with the trends in economic historiography'. In other words they can enjoy a period of grace during which they can se mettre 'a" la page. Nobody can deny that the sect has acquired a good many new disciples in the last few years. 2 And this is the reason why I feel some compulsion to write about some of the arguments presented in this recent article. I want to leave out, however, from the present discussion Professor Lopez's argument that 'this slackening [in the economic expansion of Europe] may also have occurred in China and the rest of the Old World'. According to him the worldwide scope of the depression was 'perhaps not without some relation to the general medical and climatic history of the age' (p. 408). 'Perhaps radiations ought also to bear their responsibility when we have learned how to assess them' (p. 409 n.). I know little about China and nothing at all about 'radiations'. I will therefore restrict my remarks to those sectors and those traditional types of causal relationships with which I am more especially familiar. I must confess that a critical appraisal of the paper of Professor Lopez and Mr Mfiskimin is not easy because often the two stagnationists state facts and circumstances without explicit reference to their source of information. On page 41O, for instance, R. S. Lopez states that 'in more than one sector there is evidence that output contracted more sharply than population', but he does not say to which sectors he refers, nor does he disclose the sources of such an important piece of information. On page 4 I I he says that 'the emergence of the problem [of unemployment] is pointed out by such facts as the relief