This book is of high topicality, due to the widespread use of informatics in hardly formalized disciplines such as sociology, life sciences etc., in which problem solving requires special tools of formal inference and plausible reasoning. The book describes the theory, methodology and algorithmization of a new approach, and some of its applications realized in the form of intelligent systems, e.g. for sociology, life sciences, etc.The main subject developed in the book is cognitive reasoning integrating three types of inference: context dependent induction, causal analogy and a new formalization of abduction. Many valued logics in particular with constructive generation of truth values provide efficient tools to handle uncertainty similarly to fuzzy logic. A method of automatic iterative hypothesis generation is proposed by the use of cognitive reasoning.