 This conclusion is compatible with holding that a proper description of \(S\)’s behavior should refer to circumstances external to \(S\). For example, describing \(S\) as reaching for a glass of water may not be appropriate unless \(S\) believes the glass contains water; and that this is what \(S\) believes may depend on circumstances external to \(S\). But then, it is at least tempting to conclude that it cannot be the intentional character of \(S\)’s belief that is causing the extension of \(S\)’s arm toward the glass. After all, \(S\)’s twin-earth double has, in some sense, a different belief (one that refers to XYZ) but the internal bodily story of the causation of the double’s arm-extension will be exactly the same as the story for \(S\) (up to substitution of XYZ in the double’s body wherever \(S\) has an H2O molecule).