Towards the end of the seventies of the twentieth century American philosopher Matthew Lipman and his colleagues developed a method of philosophical inquiry with children and the youth, which, according to the author, allowed to supply inefficient system of education in the areas of supporting intellectual and social development of children. The Philosophy for Children scheme was aimed to develop critical thinking skills, reasoning, argumentation and dialogue. The idea of philosophizing with children in school has become an inspiration for many educational experiments carried out in various parts of the world. An important part of these experiments is the scheme’s evaluation, the aim of which is to investigate the effectiveness of the method and its impact on intellectual, emotional and social development of children. The article analyzes the 4 selected European researches, concerning the measurement of the impact of philosophical investigations on the development of children cognitive competence. It presents the basic methodological assumptions, the course of study and the results and conclusions of experiments. All of these experiments demonstrate the positive impact of methods to support the intellectual development of children. Despite this, the method is still seen only as an educational experiment and there is not wider application in education. From the analysis of research reports one can conclude that there is a need for in-depth and systematic study of the method of philosophical inquiry in education, inclusion in the study area, not only the effect of the impact of the program on children’s competence but also on the competence of teachers and broadly understood culture of the school.