Abstract
The article shows a difference in Aristotle's ethical theory between the Protrepticus and Eudemian Ethics on the one hand and the Nicomachean Ethics on the other. The difference is explicated by means of the interpretation of the concept of ὅρος (standard) in these writings.
The Protrepticus and Eudemian Ethics present ethical theory as an expertise which - together with other sciences - has a standard for decisions and actions taken from nature and the divine. The ethical theory presented in the Nicomachean Ethics does not entail such a strong concept of ὅρος and it treats ethics in contrast to other, more exact, sciences.
Finally, the article presents a tentative suggestion as to why it seems that the Nicomachean Ethics VI,1 raises hopes that it will provide a detailed account of ὅρ ος when in fact there is no discussion of it.