In Aristotle's ethics and anthropology the concept of normality or regularity, nature and norm subtly imply each other reciprocally.
The ethical criterium, explored throughout Nicomachean Ethics is that illustrated in detail by the "normal" conduct of the so called spoudaios. The point of contact between normality and naturalness is on the other side offered by the concept of physis, analysed both in Physics and in the biological works. Nature is what happens for the most, i.e. within the field of regularity and legality which characterises its processes.
But nature at the same time means telos, i.e. the finality and completion of these processes. What is normal is therefore also natural, and what is natural represents the normative level of phenomena. As for the ethical and anthropological field, the normal-natural human condition, and therefore the law which defines man's perfection, can be traced in the human political nature, i.e. in man's complete adjustment to the model given by the spoudaios. What falls outside this virtuous circle of normality, naturalness and legality is considered a moral deviation, which at the same time constitutes a teratology for and of mankind.
Accordingly, conformity to the naturalized public ethos excludes in Aristotle any recourse to the transcendental norm of the "ought to be" which had been one of the fundamental characteristics of Plato's ethics.
