**1. Introduction**

People frequently say that the objective of scientific research is to pursue knowledge to take appropriate action over the world. Adhering to this principle involves special epistemological procedures both as regards the information selection and how it is organized. This document will discuss the diagnosis and decision-making activities, in complex systems. The six sections of this chapter aim to introduce a few fundamental properties to be taken into consideration in the action choices. Section 1 emphasizes that the choice of action is a mental (cognitive) construction to be performed in each occurrence. Section 2 presents the paradigm as a tool for processing information. Section 3 examines the structure of paradigms that aim *objectivity*. In Section 4, examined paradigms aim to ensure that the action is adequate and *appropriate* to achieve the desired result. Section 5 recommends a change in format to study societal or group decision makings. Section 6 analyses decision-making as a dynamic process made from

interactions between sub-systems. Section 7 evaluates the possible consequences of the notions of complexity and dynamism on the subsequent evolution of psychology.

Various epistemological processes will be analyzed, not only as regards their intrinsic content (the case being processed), but also with respect to their contribution to the general evolution of the discipline toward new conceptions and innovative epistemological repositioning using systems rather than variables.
