I think Chapter 5, Forms of Theories, is a key chapter in the rest of this book. I learned three different conceptions of how sets of statements should be organized so as to constitute a theory. These are set-of-laws, axiomatic, and causal process. I especially concentrated on this part to understand each example and distinguish the difference between conceptions.  In terms of set-of-laws author insists that if scientific knowledge is organized in the form of a set of laws, a scientist cannot achieve all the purpose of science, since he cannot provide a sense of understanding. The axiomatic theory is defined as an interrelated set of definitions and statements and one of the most important problems in dealing with theories in axiomatic form is determining how to select the axioms. Also it can provide a sense of understanding, but not always. The causal process form has the major difference between this form of theory and the axiomatic form. That is all statements are considered to be of equal importance.

Author also indicates that while a conception of theory as a set of laws will lead to an efficient use of resources if the research-then-theory strategy is employed, a theory in axiomatic or causal process form will lead to an efficient use of resources if a theory-then-research strategy is employed. Another interesting part is a comparison between strategies, research-then-theory and theory-then-research, in chapter 7. Author explains that research-then-theory strategy has the disadvantage that considerable effort may be spent on collecting data that have no useful purpose, but it may provide some information useful for inventing theories and theory-then-research strategy also has the disadvantage that the scientist may have no initial information on which to base the first attempts at a theory, but research is more efficient when one only collects information related to a few important hypotheses.

Chapter 8, conclusion, is very good to remember key points in this book. While I read this chapter I could arrange whole procedure to constitute a theory with abstract theoretical statements.