M ARKUSEN A. (2003) Fuzzy concepts, scanty evidence, policy distance: the case for rigour and policy relevance in critical regional studies , Reg. Studies 37 , 701-717. Regional analysis is increasingly populated by fuzzy concepts that lack clarity and are difficult to test or operationalize: flexible specialization, windows of opportunity, resurgent regions, world cities, cooperative competition. Many analyses rely on anecdote or singular case studies, while contrarian cases and more comprehensive and comparative inquiries are ignored. Methodology is often not discussed adequately. This trend has been accompanied by an increasing detachment from political and policy advocacy. In this paper, I define fuzzy concepts and relate their proliferation to an emphasis on process rather than institutions, agents and behaviour. To demonstrate my arguments, I review three highly acclaimed bodies of work - flexible specialization with its re-agglomeration thesis; world cities; and "cooperative competition' in industrial districts a la Silicon Valley. The paper makes the case for adherence to social science norms of conceptual coherence, causal theory (with both behavioural and structural components) and subjection of theory to the rigours of evidence, where the latter may encompass qualitative and quantitative techniques. Greater commitment to entering the policy debate and to making results accessible and informative to policymakers, regional planners and political activists would substantially strengthen this body of research and its usefulness. M ARKUSEN A. (2003) Des concepts confus, de maigres preuves, des politiques eloignees: les arguments en faveur de la rigueur et des politiques pertinentes dans les etudes regionales critiques, Reg. Studies 37 , 701-717. De plus en plus l'analyse regionale est peuplee de concepts confus qui manquent de la clarte et qui s' averent difficiles a tester et a mettre en oeuvre: la spe cialisation flexible, les nouvelles possibilites, les regions renaissantes, les grandes villes a l'echelle mondiale, la concurrence cooperative. Beaucoup des analyses reposent sur des etudes de cas anecdotiques ou exceptionnelles, tandis que l'on ne fait aucune attention ni aux etudes de cas opposees, ni aux enquetes plus detaillees et comparatives. Souvent, la methodologie n'est pas discutee convenablement. Cette tendance va de pair avec une separation accrue du plaidoyer politique et de principe. Cet article cherche a definir des concepts confus et a rapporter leur proliferation a l' importance accordee au processus plutot qu'aux institutions, aux agents ou au comportement. Afin de le demontrer, on fait la critique de trois faisceaux d'oeuvres qui recoivent un excellent accueil - la specialisation flexible, avec sa these a propos de la notion de reagglomeration; les grandes villes a l'echelle mondiale; et la notion de "concurrence competitive' dans les districts industriels, a la maniere de Silicon Valley. L'article prone en faveur de l'adhesion aux normes de la science sociale quant a la coherence concept...