ABSTRACT
This introduction presents an overview of the key concepts covered in the subsequent chapters of this book. Curiosity, inquisitiveness even, and a reflective bent of the mind are very general attributes of human nature. It is very reasonable to argue that the subjects most discussed are precisely those that are inconclusive. Certainly we have every reason to be proud of the human intellect for devising conclusive arguments in mathematics, in logic, and in other places where it is admitted that such arguments are to be found. The chapter explains why mere mention of 'common sense' and of the 'plain man' is open to the most various constructions. These observations indicate, and in a measure may serve to defend, the general standpoint occupied by this study. The need for continuous discussion of these topics is precisely the necessity for mastering principles in our own time, and for applying them to the needs of our own generation.
