Abstract
This paper focuses on Aristotle's methodology of science and its application to the study of the human soul. My aim is to contrast two significantly different methodological approaches and to formulate two pairs of premises that Aristotle employs in two clearly differentiated and independent fields of study, namely in his zoological works and in the works of practical philosophy.
Acknowledging these principles, as I suggest, may shed a new light on the methodological difficulties that Aristotle indicates in the introductory chapters of his De anima.