In Part I, I have discussed the historical difficulties with understanding the Aristotelean concept of cause (aitia). I show that the Aristotelean concept of cause (aitia) is different from the 'usual' conception of causation, where the 'usual' conception of causation is that proposed by Hume or Reid. I also show how Aristotelean teleology gets wrongly associated with backward causation, design arguments, etc. In Part II, I show how contemporary functional explanations (in Larry Wright's sense of the term 'function') are really a subset of Aristotelean teleological explanations. In Part III, I argue that a living organism's particular genotype is the feature containing the potentials which are actualized through growth and change, making the adult form of the organism. In this way, I maintain that the genotype can be seen as the feature in which the efficient, formal, and final aitiai coincide, as Aristotle suggest they do in the Physics II.7. Thus, the genotype of an individual can be regarded as a teleological principle which directs the changes in the immature organism toward being a mature organism in accord with that organism's internal essence. This view, I argue, makes Aristotle compatible with contemporary genetic theory
