In recent years, the topic of trust in public authorities has been extensively analysed, notably with regard to the impact that this has on countries’ development. In this paper, an analysis of three representative European countries (Spain, Denmark, and Belgium) is carried out using data from the European Social Survey. The application of a method based on fuzzy logic and the degree of similarity to the ideal solutions makes it possible to obtain a synthetic indicator of the degree of confidence that the citizens of these respective countries have in the analysed institutions. This analysis is based on six different dimensions, namely: (1) The National Parliament; (2) The Legal System; (3) The Police; (4) The Politicians; (5) The European Parliament; and (6) The United Nations. The results obtained are conclusive for the current situation of the European Union, and in particular for Spain, where there are indications that the current democratic system is being undermined by the lack of trust that citizens have in their respective public authorities and institutions.