After we have some senses about what theory, idea, concepts, and statement are, the rest of book continues discussing the forms of theories, testing theories, and strategies for developing a scientific body of knowledge.   

In chapter 5, the author introduces three different kinds of conceptions and their advantage and disadvantage when dealing with the purpose of science. When talking about the set-of-laws form, there is an example of “The Iron Law of Oligarchy”. It is easy to understand the descriptions of “Social system” and “Democratic leadership”, but I am confusing about the concept about “Oligarchical leadership”. According to Michels, the only stable form of leadership is an oligarchical leadership. I just want to know what kind of leadership in USA right now. Everybody knows that USA is the democratic country, but it is looks like an Oligarchical leadership in USA based on the description in the book.

In chapter 6, I continue learning the testing theories. I am very interesting in “it is never possible to prove an abstract statement true for all possible situations as long as future situations are within the scope of the statement.” This is very important for us to do the research in the future. We cannot focus on determining abstract statement either true or false, but try to increase the degree of confidence based on the empirical research.

The rest chapters also gave me a great knowledge about the strategies of research. The two important approaches are research-then-theory and theory-then-research. The author gave a lot of examples to discuss the advantage and disadvantage of both methods. But I like the comparison of them, which can increase the advantage and decrease the disadvantage.