The document introduces the Cartesian Questions method for making decisions. The method involves asking four questions to examine a decision from different angles: 1) What will happen if I do this? 2) What will happen if I don't do this? 3) What won't happen if I do this? 4) What won't happen if I don't do this? The document provides an example of how the author used this method to evaluate spending money on an expensive mentorship program. Considering the responses to the four questions helped the author determine the best decision was to enroll in the program.