P. WILLIAM BECHTEL INDETERMINACY AND UNDERDETERMINATION: ARE QUINE'S TWO THESES CONSISTENT? 1 (Received 29 November, 1979) In 'On the Reasons for the Indeterminacy of Translation' Quine employes the thesis of the underdetermination of theories as a premise in his main argument for the indeterminacy of translation. 2 In that paper and earlier works, 3 Quine presents plausibility considerations for the thesis of the under- determination of theories, but does not concern himself with providing a precise account of or argument for the underdetermination thesis. In a later paper, 'On Empirically Equivalent Systems of the World',4 Quine attempts to state and defend a more precise account of the underdetermination thesis, but he does not seem to recognize that this later account of the underdeter- mination thesis is inconsistent with the thesis of the indeterminacy of transla- tion. This inconsistency has the consequence of undermining any attempt to argue for the indeterminacy thesis on the basis of the underdetermination of theories as he now articulates that thesis. The main objective of this paper is to show how Quine's more recent account of the thesis of the underdetermination of theories invalidates his argument for the indeterminacy of translation that was made to rest on the underdetermination thesis. To set the stage for that argument, though, in Section I, I will show how Quine thought, at the time he wrote 'On the Reasons for the Indeterminacy of Translation', that the underdetermination thesis provided an argument for the indeterminacy of translation. In the Section II, I will explicate Quine's articulation and defense of the underde- termination thesis in 'On Empirically Equivalent Systems of the World'. In Section III, I will first show formally how Quine's theses are inconsistent and then analyze how this inconsistency emerged. I Quine's main endeavor in 'On the Reasons for the Indeterminacy of Transla- tion' is to argue from the underdetermination of theories to the indeter- Philosophical Studies 38 (1980) 309-320. 0031-8116/80/0383-0309501.20 Copyright 9 1980 by D.Reidel Publishing Co., Dordrecht, Holland, and Boston, U.S-4.