Full Idea
What makes the metaphysical realist a 'metaphysical' realist is his belief that there is somewhere 'one true theory' (two theories which are true and complete descriptions of the world would be mere notational variants of each other).
Gist of Idea
Metaphysical realism is committed to there being one ultimate true theory
Source
Hilary Putnam (Why there isn't a ready-made world [1981], 'Causation')
Book Reference
Putnam,Hilary: 'Realism and Reason: Papers vol 3' [CUP 1985], p.211
A Reaction
This is wrong!!!!! Commitment to one reality doesn't imply that only one comprehensive theory is possible. Theory-making (at least in any human language, or in mathematics) is an inherently limited activity.
Related Ideas
Idea 17648 It is an illusion to think there could be one good scientific theory of reality [Putnam]
Idea 12598 Reality is the overlap of true complete theories [Harman]
Idea 14334 Modest realism says there is a reality; the presumptuous view says we can accurately describe it [Mumford]