Electrolysis on Twin Earth

he Twin Earth thought experiment is meant to show that meaning is not fixed by what is inside the speaker’s head. Oscar on Earth and Twin Oscar on Twin Earth are stipulated to be psychologically identical. Each uses the word water for the clear, drinkable liquid that fills lakes, falls as rain, freezes in winter and boils in kettles. Yet on Earth the liquid is H2O, while on Twin Earth it is XYZ. The thought experiment becomes unconvincing once we consider some properties of H2O that cqnnot hold for Twin Oscar’s XYZ . Electrolysis is a good example. Consider the sentence: electrolysis of water produces hydrogen and oxygen. On Earth, this sentence is true. If the Twin Earth liquid is XYZ, and if XYZ has a different chemical composition, the corresponding Twin Earth sentence is false