Versión en inglés del texto: “Problemas en el análisis de la percepción pública de la biotecnología: Europa y sus contradicciones” que será publicado en el libro Percepción social de la ciencia, en curso de edición por la Academia Europea de Ciencias y Artes (Delegación Española).The problems of the public's perception of science and technology cannot be separated from the new socio-political context in which science and technology is developing. These new “environments” demand new conditions and qualifications from experts. The measurement of society’s understanding of science and technology has been tackled with questionnaires which stumble on evident problems when they have to face the complexity of scientific activity and its reflection on what can be understood as “scientific culture”. A critical review on the different facets in the analysis of the public’s perception of science reveals the need to propose new schemes and techniques in order to advance in this area of knowledge. Biotechnology is a clear example of all these issues, with results which emphasize the heterogeneous nature and ambivalence of the European positions. The interpretation of these results encounters a lot of difficulties. The dissection of the transgenic food controversy, chosen as an example, has allowed the identification of five blocks of comparison and controversy: confidence, risk and benefits, interests, rationalities and values.Peer reviewed