The third volume of the book series, The Crisis of Bourgeois Ideology, and the Doctrine of the Mode of Thinking, deals with the crisis of bourgeois natural science. Natural scientists generally are held in high esteem in bourgeois society because they are seemingly apolitical, unimpeachable, and committed solely to social progress. With the advance of positivism and pragmatism, however, the natural sciences lost much of their scientificity and have gotten into a crisis. This polemic is intended to revive materialistically based free thinking in the working class. Unless it frees itself from the shackles of idealism and metaphysics, humanity will not be able to utilize the achievements of the modern natural sciences for social progress. Thus, this book is also a must for every scientist with a critical mind. It serves the purpose of helping scientific socialism and its dialectical-materialist method gain new esteem.