Notes of Philippa Foot

In Virtues and Vices,

Almost any desire can lead a man to act unjustly, not even excluding the desire to help a friend or to save a life, whereas a cowardly act must be motivated by fear or a desire for safety, and an act of intemperance by a desire for pleasure, perhaps even for a particular range of pleasures such as those of eating or drinking or sex.

As with courage and temperance so with many other virtues: there is, for instance, a virtue of industriousness only because idleness is a temptation; and of humility only because men tend to think too well of themselves. Hope is a virtue because despair too is a temptation;

With virtues such as justice and charity it is a little different, because they correspond not to any particular desire or tendency that has to be kept in check but rather to a deficiency of motivation; and it is this that they must make good. If people were as much attached to the good of others as they are to their own good there would no more be a general virtue of benevolence than there is a general virtue of self-love. And if people cared about the rights of others as they care about their own rights no virtue of justice would be needed to look after the matter, and rules about such things as contracts and promises would only need to be made public, like the rules of a game that everyone was eager to play.