This article seeks to clarify the concepts of risk and uncertainty, restricting its focus to environmental problems and to three strands of reflection. Firstly, I suggest that we should apply the label riscophrenia to the tendency to envisage most environmental problems excessively in terms of probabilistic risk, erecting the concept to a core dogma of certainty based on the image it offers of (alleged) safety and control of the random. Looking at the most serious environmental problems of the twenty-first century through the prism of "animal spirits" is above all an exercise which shows that unpredictability and uncertainties are constituent elements of human existence and social life. Secondly, I argue that the assessment of uncertainty has political and normative implications. I hold that uncertainty may make it possible to invoke precautionary, not just preventive, measures, and that alternative "contextualised" research strategies, open to a variety of points of view, are possible. Lastly, I claim that the language of risk and its excessive application is generally laden with a type of ambiguity which tends not to emphasize society's current problems, and so facilitates the continuation rather than the questioning of our society's dominant technocratic and technological model.

O conhecimento científico mobilizado pelos peritos em apoio ao processo decisório constitui um recurso valioso. Contudo, a peritagem não é imune a apropriações políticas nem deixa de ter os seus próprios limites epistémicos. Por isso, é questionável concebê-la como sendo o único meio para assegurar a legitimidade de uma dada decisão. A este propósito, não é indiferente que os peritos realizem análises científicas baseadas numa concepção probabilística de risco ou numa outra que pondere as incertezas e a ignorância.

La connaissance scientifique mobilisée par les experts pour étayer le processus de décision est une bonne ressource. Toutefois, l’expertise n’est pas immune aux appropriations politiques et possède également ses propres limites épistémiques. C’est pourquoi elle ne devrait pas être conçue comme étant le seul moyen d’assurer la légitimité d’une décision donnée. Et il n’est pas indifférent, à ce propos, que les experts fassent des analyses scientifiques basées sur une conception probabiliste du risque et sur une autre conception susceptible de peser les incertitudes et l’ignorance.

Scientific knowledge used to assist decision-makers is a valuable resource. However, expertise is not immune to political appropriation, and has its own epistemic limitations. It is therefore questionable to regard expertise as the only method of ensuring that any given decision is legitimate. In this connection, it makes a difference whether experts carry out their scientific analysis on the basis of a probabilistic conception of risk, or on a different basis which takes uncertainties and ignorance into account.