ABSTRACT
This chapter focuses on both philosophical and psychological issues that bear on the process of science. Philosophical issues concern the nature of science, what constitutes the scientific knowledge. Psychological issues concern what is known about thinking and reasoning and how it may influence scientific thinking, especially through the operation of cognitive biases. The chapter discusses the nature of logical or deductive inference. The important point is that deductive reasoning is required to generate predictions and test hypotheses. A hypothesis is established in a set of experiments or else follows from a well-established theory. The chapter provides some discussion of the psychological nature of hypothetical thinking and several well documented cognitive biases that are associated with it. It also points out the statistical nature of psychological science, which is one of the reasons why it can be hard to apply logical systems such as Popper's falsificationism. The Popperian philosophy advocates falsificationism, which is based upon valid logical argument.
