A paper of mine with the above title has been accepted for publication in the Swedish journal Theoria. It’s an old journal and not at all bad, although not really world class either. Wiley-Blackwell acquired it recently. Anyway, I thought it would be appropriate as Kripke’s latest paper was recently published there. There’s also a paper by Nick Zangwill in a recent issue. My paper was under review for quite a long time (since October 2008), and I have thought about the matters that I discuss in this paper in more detail. In the light of that, this paper is really just an introduction. However, it is 7,000 words long in any case, so I couldn’t have extended it much more. I’ve posted a copy of the paper here. Grab it now if you’re interested, because I will have to take it down when it appears in print. Wiley-Blackwell insists that the paper will not appear on a personal home page until 24 months after the publication. Obviously I can still e-mail it to people.

The purpose of the paper is to demonstrate that the classic Kripkean story about a posteriori necessities omits a couple of important things. The primary case that I analyse is the classic ‘Water=H20′. Basically I argue that the a priori principle that the modal content of this identity statement is grounded in has not received sufficient support. The a priori principle that I am referring to is that compounds such as water have their molecular structure by necessity, i.e. that it is part of the essence of compounds that they have the very molecular structure that they do. While this might seem like an obvious thing, it is far from clear how we are supposed to come to know this a priori principle. I discuss this in some detail in the paper, but more recently I’ve learned about some peculiar cases, such as so called non-stoichiometric compounds or Berthollides, as they are sometimes called. These are compounds which at least seemingly violate the law of definite propositions, namely they are compounds which do not always contain exactly the same proportions of elements by mass and would hence seem to cause problems for the a priori principle that compounds have their molecular structure by necessity. There is some interesting chemistry behind this, I recently had a chat about this with Robin Hendry; he has got a couple of papers about the problems concerning water. As to Berthollides, they do not seem to have been discussed in any detail in philosophical connections. I got a couple of references from another philosopher who knows his chemistry, Paul Needham (see his ‘Resisting Chemical Atomism: Duhem’s Argument’, Philosophy of Science, 75: 921-31, 2008), but this appears to be something that philosophers haven’t really picked on yet. Anyway, I plan to look into this matter in some more detail when I’ve got some time. This is also core content for the book that I am supposedly working on, so I will extend on this there at the very latest.