Books on Amazon
Kripke: In general, things about a counterfactual situation are not "found out", they are determined.
It is often said that when we describe a counterfactual situation and it cannot result in a purely qualitative one, then mysterious "mere individual things" would be assumed, featureless substrates, on which the properties are based. This is, however, not the case.
Let’s assume we use the reference of the name "Hitler" due to the fact that it is the man who killed more Jews than anyone has ever done in history.
But in a counterfactual situation in which someone else possessed this bad reputation we would not say that in this other situation the other man would have been Hitler.
Counterfactual: Even if you say "suppose Hitler had never been born", then the name "Hitler" refers here, and still in a rigid manner, to something that would not exist in the described counterfactual situation.
Remember, though, that we describe the situation in our language, not in the language that people would have used in that situation. Hesperus = Phosphorus is necessarily true (but a situation is possible in which Venus does not exist).
... But this would still not be a situation in which this woman which we call "Elizabeth II" was the child of Mr. and Mrs. Truman. It would be a situation in which there was another woman who had many of the features which actually apply to Elizabeth.
The question is: was Elizabeth herself ever born in this possible world? Let’s say no. Then Truman and his wife would have a child possessing many of the properties of Elizabeth, but in which Elizabeth herself never existed.
Name und Notwendigkeit Frankfurt 1981
S. A. Kripke
Outline of a Theory of Truth (1975)
Recent Essays on Truth and the Liar Paradox, R. L. Martin (Hg), Oxford/NY 1984