ABSTRACT
This chapter presents the modern list of 40 Principles as a problem-solving tool that is effective, easy to use, cheap, and accessible to everybody. The 40 Principles are the most popular tool of theory of inventive problem solving (TRIZ) and several books and many articles are devoted to them. The chapter shows how to select principles that will help solve particular problems, including the Contradiction Matrix as an important tool in support of the search. Principles can be selected by tradeoffs. When the tradeoff is formulated, it can be used to eliminate unsuitable principles. Innovative principles give clues for solving problems. The simplest way to use the principles is to go through them all or just randomly select them. Some selection criteria are useful for deciding which principles to use for any particular problem. Resource mapping, the description of the Ideal Final Result, and the patterns of evolution also help to find useful principles.
