This is a free, online textbook.  According to the author, "In this text it is my task to challenge the reader, to invite and to encourage the reader to think and to think critically concerning these basic and important questions and problems. I shall often present material and questions which challenge the accepted view, the predominant view, the popular view, and the view which most people acquire through their culture and assume to be not only true but the only view. The aim is to broaden and expand awareness. The aim is to develop reasoning skills and critical thinking abilities. It shall be my aim to get the reader to think about new things. This is education. I shall also attempt to provoke the reader to think about things in a new manner. This is also education but it may not be what some expect or want. It involves growth. Sometimes people resist thinking about familiar subjects in new ways. Sometimes people resist changing their minds for they fear leaving the comfort of familiar ideas for the uncertainty and disturbance of the new and different. However, sometimes it is necessary to endure some discomfort and even some anxiety in order grow intellectualy and to develop a better understanding of the matter or to solve the problem. If I succeed the reader should expect to be challenged."