ABSTRACT
In this chapter, we discuss the evolution of ideas underlying research and practice in medicine. To promote a better understanding of the subject, we also include definitions that go beyond the intuitive meaning1,2 of the basic terms used in this chapter and in those that follow:
• Models are frameworks that establish how we look at particular subjects. • Concepts are well-defined ideas drawn from a model. • Theories are sets of concepts with an objective definition and explanation of a
phenomenon of interest. A theory is a set of interrelated constructs (variables), definitions, and propositions that presents a systematic view of phenomena by specifying relations among variables, with the purpose of explaining natural phenomena 2 .
