This letter to Davidson was written as Lewis was making significant strides away from the influence of Quine and beginning to wonder whether there really might be systematic and deep indeterminacy of thought and language, as Quine had claimed. By the time of “Radical Interpretation” (Synthese, vol. 23, 1974), Lewis had decided to “hold the line” against any such indeterminacy arising. Here in 1970 we see Lewis speculating about how he might take steps in this direction. (© Estate of David K. Lewis.)