Kripke, Naming and Necessity [Alberto Torrigiotti]

"'Possible worlds' are stipulated, not discovered by powerful telescopes. There is no reason why we cannot stipulate that, in talking about what would have happened to Nixon in a certain counterfactual situation, we are talking about what would have happened to him."

Kripke argues against the transworld identification thesis, i.e., the view that in talking about an object in other possible worlds, we must determine whether the object would be the same object. To illustrate an example, suppose I want to stipulate a possible world in which George W. Bush did not become the 43rd president of the United States. First of all, I'm certainly not saying that the 43rd president of the United States did not become the 43rd president of the United States, and furthermore, it isn't a matter of discovery or investigation into the characteristics that constitute the identity of Bush whether the object I'm calling Bush in this possible world is still Bush; the need to identify across worlds is bypassed through stipulation.

As far as I am aware, talk of possible worlds in the philosophical sense is indeed stipulative and my agreement with Kripke on this point is strengthened by the following consideration. It is not by virtue of any description or body of descriptions of Aristotle that I come to assign him the proper name "Aristotle", so the name "Aristotle" is used to refer to that man over there (who happens to have the characteristics of Aristotle). If for instance, I met a Greek philosopher whom I took to be the best student of Plato and the teacher of Alexander the Great and called him "Aristotle" only to find out that the best student of Plato and teacher of Alexander the Great is actually Jones, I wouldn't say to Aristotle "Oh I'm mistaken, you are not Aristotle", nor would I say to Jones, "You are the real Aristotle".

"But a simple answer to the question is this: Even if this is the only standard of length that he uses, there is an intuitive difference between the phrase 'one meter' and the phrase 'the length of S at t₀'. The first phrase is meant to designate rigidly a certain length in all possible worlds, which in the actual world happens to be the length of the Stick S at t_0."

Even if we fix the reference of 'one meter' to the length of S at t₀, the meanings of the two phrases 'one meter' and 'the length of S at t₀' are not synonymous. There is, for Kripke, an important difference between the functions of giving a phrase meaning and fixing a phrase's reference. 'One meter' is a rigid designator which purports to hold across all possible worlds, whereas 'the length of S at t₀' is not because the length of S at t₀ could have been a different length from the one we used to fix the reference of one meter.

I am having difficulty finding a compelling a reason to believe the bolded portion of the quote, but I don't disagree with it. Kripke compares this to the example of water boiling at 100°C, but in the case of water boiling it is more obvious that 'the temperature at which water boils' is a rigid designator, and that '100°C' just fixes its reference. Why does 'one meter' designate the same object across all worlds? I think I have some inkling of what Kripke would say, but it would be helpful if someone could explain.