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.

Many philosophical questions have not yet found an accurate answer, but we cannot say that philosophical questions are questions that can never be answered. There are many questions that have no answers, such as ancient mysteries, theological issues, UFO issues, and many other mysterious phenomena, but these are not philosophical issues. On the contrary, philosophical issues can have answers. For example, the standard of truth, with the development of philosophy of science and technology, has gradually formed a lot of consensus.

There will be mistakes in theories, people will be led astray, and even disasters, but we cannot completely abandon theories and we cannot give up the efforts to improve theory. The unity of believe and doubt, and the unity of pragmatism and ideal is a scientific attitude toward theory.

When we encounter pains and difficulties in life, we need help from science, but scientists have found that they must resort to philosophy. Otherwise, scientific theories cannot be justified. The important conclusion in science is called the theorem, but how do you prove various conclusions and theorems? Many of the theorems seem to be clearly correct, but they are later overturned. For example, how many parallel lines can be made through a point outside a straight line. There is only one in Euclidean geometry, and there are countless lines in non-Euclidean geometry. Originally, everyone thought that the material is immortal, and later found that positive and negative particles can disappear together; we used to believe that particles are real, and later Quantum mechanics says that the appearance of particles is a probability. Then will all theories be overturned in the future? Are there any unchanging truths? In the end, what is truth and how to prove the truth? Scientists must ask philosophers for advice about these questions.