Ontological maximalism
In philosophy, ontological maximalism (or metaontological maximalism) is a ontological realist position that asserts, "whatever can exist does in some sense exist". Overview 
Meta-ontology deals with question related to ontology, whether there are mind independent (objective) answers to "what exists". Ontological realism assert reality (at least a part of it) are independent of human mind. In contrast to realists, Ontological Anti-realists deny the world is mind-independent. Believing the epistemological and semantic problems to be insoluble, they conclude realism must be false. Maximalism is one of two main metaontological position. On maximalist framework, any entity whose existence is consistent with the nature of this world can be taken to exist. See also 
Ontology
Large cardinal property
Continuum hypothesis
Mathematical universe hypothesis
Modal realism

References 
Set theory
Ontology