How to Read a Book: the classic guide to intelligent reading

by Mortimer J. Adler

fact, this is irrelevant to the point, although a book about economics that is not true is a bad book. Strictly speaking, any ethical work teaches us how to live our lives, tells us what we should do and not do, and often informs us of the rewards and punishments attached to doing and not doing it. Thus, whether or not we agree with its conclusions, any such work is practical. (Some modern sociological studies merely report the actual behavior of men, without judging it. These are neither ethical nor practical books. They are theoretical works—works of science.) Similarly with a work on economics. Apart from reportorial, mathematical, or statistical studies of economic behavior, which are theoretical rather than practical, such works usually teach us how to organize our economic life, either as individuals or as societies or states, tell us what we should do and not do, and also inform us of the penalties involved if we do not do what we should. Again, we may disagree, but our disagreement does not make the book unpractical. Immanuel Kant wrote two famous philosophical works, one called The Critique of Pure Reason, the other, The Critique of Practical Reason. The first is about what is and how we know it—not how to know it, but how we in fact do know it—as well as about what can and cannot be known. It is a theoretical book par excellence. The Critique of Practical Reason is about how men should conduct themselves and about what constitutes virtuous or right conduct. This ...