Aristotle (384 B.C.E.-322 B.C.E.), who is without doubt one of the most important philosophers of the history of philosophy is also one of the most important names in history of science. During his era, science and philosophy were still one inseparable entity. In addition, he was the first philosopher who had suggested the principles of scientific reasoning and the approach of a scientist to nature that well-organized. The theory of four causes is the basis of these principles. In this thesis the relation between the four causes theory and one of the most comprehensive discussions of contemporary biology –what is the phenotype and how does it occur- has investigated. The research of the complex pathways of interaction net between genotype, phenotype and environment needs causal investigation which involves more than a single cause. This investigation is similar to the investigation of Aristotle’s material, formal and efficient causes altogether.