According to Aristotle (as noted here), the nature of virtue is to seek a mean or middle between extremes, which is an intermediate state between them.
These contrary extremes are often called vices, but that implies the operation of evil, which is contradictory to the good, and should be completely rejected. It would be better to call the contrary opposites semi-virtues as we shall see.
The issue concerns two goods that are contraries in some way so that preferring the one reduces the other and vice versa. In order to affirm both one must seek an intermediate state between them that balances their legitimate value. Let’s look at an example often used:
With respect to acting in the face of danger, courage is a mean between the excess of rashness and the deficiency of cowardice.
That is to say:
With respect to acting in the face of danger, courage is a mean between acting excessively imprudent, which would be rash, and acting excessively prudent, which would be cowardice. Thus courage is a mean between prudence and imprudence in action.
The contraries of prudence and imprudence are not vices, but neither are they virtues to be affirmed in general. In some way they are excessive, or from the opposite perspective, deficient.
Call them semi-virtues, for they are partially virtuous, but are not fully virtuous by themselves. They are imbalanced alternatives to the real virtues.
This is applicable to political life as well. Liberty and equality are both goods that are opposites in some ways. Liberty allows the inequality of abilities and interests to induce inequality in society. Equality stifles these differences, but that entails a loss of liberty.
Thus liberty and equality are semi-virtues in political life. Political virtue is a mean between these contraries. It doesn’t have a name but is a balance between liberty and equality. It is a centrist politics.
One further note concerning virtue ethics and theology: God has no contrary (one might say it’s nonbeing but that’s another way of saying it’s nothing). So in relation to God, there is no middle state. The problem is not contraries but contradictories: good and evil, righteousness and sinfulness, truth and falsehood. The former is to be unreservedly affirmed, and the latter unreservedly rejected.