Introduction

This chapter is not just concerned with theories but with theory. The theory refers to the knowledge and understanding that you build up about research topics based on scholarship and hard thinking about research findings. All researchers must develop theory in the sense of knowledge and understanding of the phenomena they study. The chapter includes technical and philosophical issues surrounding the formulation and testing of theories. Grand theories, or meta-theories, are tested through application of more specific theories and models to empirical tasks. Researchers will normally develop theories later in their careers having first explored causal relationships through empirical research. Scientific theories build on causal relationships and typically incorporate hypothetical constructs and intervening variables. A psychological theory usually concerns the nature of mental processes in a particular domain, many psychological theories develop top-down manner. The majority of psychological theories still tend to be implicitly statistical and hard to refute in the strict Popper an sense.