Devitt and Fine (notes) I am very thankful to prof. Devitt for his patience in answering my questions. He corrected many of my misunderstandings on his arguments. Of course I am responsible for remaining misunderstandings (if any) in this paper.
 Surprisingly enough, Fine uses van Fraassen as a paradigm case of instrumentalism, but of course van Fraassen is not an instrumentalist in the exact meaning of the word. Instrumentalism reinterprets scientific statements as something else, while van Fraassen claims that science should be taken literally. See van Fraassen 1980, 9-13.
 Devitt might reply that anti-Realistic traditional alternatives like phenomenalism have other difficulties, so they cannot be saved by this move. Of course phenomenalists failed to translate physical object language into phenomenal language. But maybe they have other virtues over Realism to compensate this failure. My point here is that we cannot easily dismiss any alternative without absolute criteria like the sceptical problematic. What we need is detailed comparisons among alternatives.
 My argument in this section owes much to Putnam (1981)'s argument against correspondence theory of truth. But my intention here is not to refuse correspondence theory of truth, but to refuse the existence of correspondence prior to the introduction of correspondence theory of truth (so my argument is much less ambitious than Putnam's). For my own analyses on Putnam's argument and on Devitt's reply, see Iseda (1995) (Alas, it is Japanese, I am sorry).
 It is easy to make up other ontologies compatible with the 'parasitic' theory. We can take any subset of the entities posited in T, and declare that these are the only real existence and other entities in T are mere empirical regularity. For example, it is possible that our observations related to electrons are really about electrons out there, while at the same time our observations on positrons are mere empirical regularity without 'real' positrons behind the phenomena. Actually this kind of selective ontological commitment is not so implausible as it seems at first. When Devitt says that instrumentalism is an appropriate attitude for some fields of science (RT, 131-132), what he is doing is this kind of selective ontology. To allow such a selection leads to underdetermination.