Complexity and nonlinearity are prominent features in the evolution of matter, life, and human society. Even our mind seems to be governed by the nonlinear dynamics of the complex networks in our brain. This book considers complex systems in the physical and biological sciences, cognitive and computer sciences, social and economic sciences, and philosophy and history of science. An in­ terdisciplinary methodology is introduced to explain the emergence of order in nature and mind and in the econ­ omy and society by common principles. These methods are sometimes said to foreshadow the new sciences of complexity characterizing the scientific deve10pment of the 21 st century. The book critically an­ alyzes the successes and limits of this approach, its sys­ tematic foundations, and its historical and philosophical background. An epilogue discusses new standards of eth­ ical behavior which are demanded by the complex prob­ lems of nature and mind, economy and society.