Monism attributes oneness or singleness to a concept, such as existence. Various kinds of monism can be distinguished:
Adi Shankara with Disciples, by Raja Ravi Varma (1904)
Ontology is the philosophical study of being. It is traditionally understood as the subdiscipline of metaphysics focused on the most general features of reality. As one of the most fundamental concept
Willard Van Orman Quine used the concept of ontological commitments to analyze theories.
Martin Heidegger proposed fundamental ontology to study the meaning of being.
Plato (left) and Aristotle (right) disagreed on whether universals can exist without matter.
William of Ockham proposed Ockham's Razor, a principle to decide between competing theories.