Revised version of "The test of proof, photography and the UFO phenomena", master's thesis defended in 1994 at the University of Paris 8, under the direction of André Rouillé.
The first part of this work is devoted to a historical approach by analyzing the discourses carried on the photographs of "UFOs" rather than studying the photographs themselves. A second part focuses on the photographs published in two specialized periodicals: Lumières dans la nuit and Inforespace. What are these forms supposed to correspond to the UFO? Is it possible to describe them? What knowledge is necessary for the interpretation of the photographs? Can they be classified? What do they represent and what do they show? Do they prove anything? What are the criteria, what are the methods used? How to advance in the analysis?