As Pranas and Gehl wrote in  1990, the “main objective of any empirical science, beyond a mere description of empirical phenomena, is to establish, through laws and theories, general principles by which the phenomena can be explained and predicted” (p. 67). Thus this chapter will  “beyond a mere description of empirical phenomena” be dealing with establishing (“through laws and theories” of course) “general principles by which the phenomena can be explained and predicted“.