The concept of identity originally comes from logic, where it designates the relationship in which each object stands to itself and to no other. In this sense one speaks of "numerical identity", because this relation forms the basis of the operation of counting, in which identical objects are counted as one object, as opposed to objects that may be arbitrarily similar but are numerically different. The relation of the numerical identity does not allow gradual increments: Two objects are either identical in the numerical sense, when they are actually one and the same object, or they are not. If, on the other hand, a person is said to have undergone a more or less profound change in their identity, then the gradual nature of this change alone suggests that claims of this type are not based on a numerical understanding of personal identity. If interpreted as statements about numerical identity, formulations such as "P's identity has changed" or "P has lost his identity" are even contradictory, because they obviously presuppose the continued existence of the person whose identity has changed or who has lost their identity. After all, the assertion of a change of numerical identity implies precisely that a new person takes the place of the original one.