What is philosophy and why is philosophy useful? Many collage admission advertisements of philosophy depart- ments say that the purpose of learning philosophy is to increase wisdom. In fact, the wisdom growth is not the main role of philosophy. To grow wisdom, it may be more effective to look at some brain teasers.

First of all, philosophy is a theory, and the role of theory is to help people to understand the world. Theory is abstract and imaginary. We must be both pragmatical and stand aloof from life. If you work everyday without thinking, then the work may be unefficient, or even worse. Second, philosophy is the most abstract theory with the least content and the greatest extent. The objective world is full of wonders and changes. If the extension of the theory is small, then we have to deal with various changes and we need a lot of theories. People's ability to read, understand, and remember is limited, and it is impossible to accept too many theories. If the extension of the theory is large, we will be able to cope with shifting events by sticking to a fundamental principle. Philosophy can explain the world's existence and laws in the most concise language, allowing people to see deeper and broader. Philosophy can unite conflicting claims to avoid being at loose ends. It is tolerable to have contradictions on minor matters, but big problems are big ones. This draw forth the other roles of philosophy: to provide rational beliefs, to solve the most important issues, to provide the most fundamental value standards, the ultimate standards of truth, and the overall world outlook, and to provide the basis for science so that science can be justified.

Because philosophy is the most extensive, philosophers must take into account all situations, many of which are uncommon. Ordinary people only care about common or current problems, so philosophers often care about problems that are different from ordinary people. What they say is always unreasonable. Philosophers seem to be strange and useless people