In the discussion of ontological pluralism, little attention has been paid to Putnam. However, he can be considered one of the leaders of this approach.The following article pursues Putnam's view on ontological pluralism,that is, pursuing the procedure that Putnam gradually moved away from metaphysical realism and eventually became an ontological pluralist.The discussion begins with Quine's ontological ideas and it is discussed how these ideas can be viewed, at least in Putnam's interpretation, as a monistic approach to ontology. Hence, ontological pluralism is, in a way, a rejection of such ideas. Then, I have dealt with Putnam's arguments against metaphysical realism, and of course its inherent monism. I have shown how his arguments presented in this article in opposition to metaphysical realism can be grouped into a single doctrine called semanticism. So this doctrine, and its relation to Putnam's pluralistic approach, is also discussed. To better understand Putnam's version of ontological pluralism, which I have called the Meaning-Based version, two other versions have been introduced: the Sorting Version, attributed to Aristotle, and the Language-Based Version, attributed to Carnap. Then, I listed one by one the differences between Putnam's version and the other two versions, especially Carnap's version. Finally, the basic components of the Meaning-Based version of ontological pluralism are discussed.
