The purpose of this book is to develop a theory and practice of education from Karl Popper's falsificationist philosophy for promoting an open society.  Specifically, the book is designed to develop an educational programme for achieving Popper's ideal of fostering critical thinking in children for full participation in an open democratic society. Arguing that Matthew Lipman's Philosophy for Children (P4C) programme can fulfil the requirements of Popper's educational ideal in schools, this study conducted an experiment to assess the effectiveness of the programme in promoting students' critical thinking in Hong Kong, China - arguably a Confucian heritage society.  The students who were taught P4C were found to perform better in the reasoning test than those who were not, to be capable of discussing philosophical problems in a competent way, and to have a very positive attitude towards doing philosophy in the classroom.  It was also found that P4C played a major role in developing the students' critical thinking. Considering that the construction of children by adults as incompetent in the sense of lacking reason, maturity, or independence reinforces the traditional structure of adult authority over children in society, it runs counter to the goal of fostering critical thinking in children.  As a way to return justice to childhood and to effectively promote critical thinking in children, this study suggested reconstructing the concept of childhood, highlighting the importance of establishing a coherent public policy on promotion of agency in children and also the importance of empowering them to participate actively in research, legal, and educational institutions.