The twelfth of 15 criticisms about forgiveness that I so frequently see is that it is impossible to even understand or define forgiveness because there are so many different definitions of it in the published literature.
This problem is not inherent in forgiveness itself, but instead is a problem with those who write about forgiveness without deeply understanding what it is. As the ancient Greeks, such as Socrates, Plato, and Aristotle, remind us, there is an objective essence (or an unchanging set of characteristics) which typifies each moral virtue. Forgiveness is what it is across historical time and across cultures and, yes, there can be individual and cultural variations in how this essence is expressed. Just because there is a ritual, for example, in Sierra Leone on the West Coast of Africa, in which a community gathers at night around a large bonfire as people forgive one another, does not mean that what forgiveness is there differs in essence from what forgiveness is in a one-on-one forgiveness therapy session in the United States. Those who think about and then write about forgiveness, according to Aristotle, can use their rational faculties to understand, even if imperfectly, what forgiveness is and is not. To forgive is to be good to those who are not good to the forgiver and this goodness includes the motivation to be good to the offending person, the cognitions of goodness toward the person, positive affect, and, when possible, positive behaviors toward that person.
