What criteria are based on the identity of two objects or concepts?

The identity of two objects or concepts is based on criteria that determine they are the same essential element, not just similar or equal in value. In programming and philosophy, several approaches are distinguished:

• Referential identity: two objects are considered identical if they occupy the same memory location (for example, in Java, the == operator for objects checks referential identity).

• Structural identity: objects are considered identical if their content or state matches (for example, the equals() method in Java).

• Logical identity: objects are considered identical if they represent the same concept or entity, even if they are physically different.

Thus, the criteria for identity depend on the context and may include comparison of references, field values, as well as semantic correspondence.