It is well known that Berkeley was content to rest his defense of Idealism on one argument; this is the so-called ‘master argument’. This argument roughly goes as follows. If objects are mind independent then it must be possible to think of an unthought of object; for what it means to be mind independent is to exist when no one is thinking about you. But this is not possible for as soon as you try you thereby think of that object and it therefore becomes a thought of object. Poor Hylas makes this mistake when he tries to think of some tree in a forrest where no people are. It is clear that he was thinking of the tree.
The intuitive response to this is that we can think of objects somehow without specifying which particular object we have in mind. But we often do this. If I tell you that I met this guy at the DMV and he said that I needed x, y, and z before I could get my license. You then think of the guy I am talking about in a way that does not specify him in thought and so you are thinking of an unthought of object. If I were to ask you who you were thinking of you could only answer ‘some guy at the DMV’ or ‘whoever your talking about’.
Don’t these kinds of purely quantificational thoughts answer Berkeley’s argument?