This book grew out of courses I gave as guest professor at the Institute for Advanced Studies in Vienna. Quantitative and mathematical approaches to the social sciences are incorporated both in the teaching curriculum and in the research approaches or that institution. However, the very fact that these approaches arc specifically mentioned in the description of the Institute's program attests to the circumstance that these methods an still not generally regarded as indispensable in the development of the social sciences as they obviously arc regarded in the development of the physical sciences. For this reason, a deliberate orientation of the social sciences toward quantification and mathematization still requires justification.