Diversity is an asset, as long as it allows cooperation. In the case of information systems and databases, the data model used is a help or a hindrance for this cooperation of diverse views; this is characterized by the semantic relativism of the model. We first analyze diversity within an information system, where cooperation is made possible by the use of external schemata; semantic relativism of the model of the database schema is the key f,ictor. Then we discuss diversity between different information systenis, where they cooperate through interoperability, by schema integration into federated schemata; semantic relativism of the canonical data model is shown to be determinant.