"Not every action or emotion however admits of the observance of a due mean. Indeed the very names of some directly imply evil, for instance malice, shamelessness, envy, and, of actions, adultery, theft, murder. All these and similar actions and feelings are blamed as being bad in themselves; it is not the excess or deficiency of them that we blame. It is impossible therefore ever to go right in regard to them—one must always be wrong; nor does right or wrong in their case depend on the circumstances, for instance, whether one commits adultery with the right woman, at the right time, and in the right manner; the mere commission of any of them is wrong. One might as well suppose there could be a due mean and excess and deficiency in acts of injustice or cowardice or profligacy, which would imply that one could have a medium amount of excess and of deficiency, an excessive amount of excess and a deficient amount of deficiency. But just as there can be no excess or deficiency in temperance and justice because the mean is in a sense an extreme, so there can be no observance of the mean nor excess nor deficiency in the corresponding vicious acts mentioned above, but however they are committed, they are wrong; since, to put it in general terms, there is no such thing as observing a mean in excess or deficiency, nor as exceeding or falling short in the observance of a mean." (Nic. Eth.1107a10-25)
When most of us discuss morality, we tend to speak about things like murder, theft, abortion, homosexual activity, etc. In other words, we speak about issues which are evil per se. To the extent that we, as a people, cannot come to a common understanding of what is evil per se and what is not, we are vicious and so is our culture. Aristotle is seeking to explain the virtues and to help people who already have decent habits to better deliberate in order to make more virtuous choices, so he is not primarily writing about actions like murder or adultery. Being a good person consists in much more than deciding what is intrinsically immoral and what is not. If we cannot not even agree on this one paragraph then how can we expect to fully understand and live out our human happiness communally?