Kripke holds that the declaration water is identical to H2O is necessarily true. According to Kripke, this true statement is only knowable through experience (a posteriori), and cannot be determined by definitions of words only. Even though it is only a posteriori, Kripke claims that it is a necessary truth that water is identical to H2O because both water and H2O rigidly designate the same stuff; in other words, they are different names for the same thing (water' picks out the same substance as H2O'). Something that resembled water in all relevant characteristics (feel, appearance, taste), but yet was not made up of H2O would be a fool's water, says Kripke . For Kripke, a truth being necessary is another way of saying that it is true in all possible worlds, and Kripke views truths like water = H2O , heat = the motion of molecules, and gold is the element with the atomic number 79" as true in all possible worlds.
In my opinion, there is something fishy about the necessity of the statement water is identical to H2O, and I wish to reject the claim that water is necessarily identical to H2O. Further, I will demonstrate the correctness of this intuition that water = H2O is contingent by presenting the following thought experiment:
[...] I find it clearly possible for water to be identical to something other than H2O and yet still be water (not ‘water' in a qualitatively indistinguishable situation where I use the word ‘water' to refer to something other than water). If a case like the above XYZ thought experiment were brought to light, and what we were faced with was what Kripke calls “fool's water” on some distant planet (that behaved just as our H2O water), what would have to be the case for it to be water in Kripke's eyes, and not “fool's water”? [...]
[...] As I have stated, water is not necessarily H2O because is a broader category name that refers to the class of things that fit the description of water. Other substances (XYZ for example) may fit the description of water, therefore making “water = contingent. But it is also the case that H2O, when not behaving like water, will cease to be water. A peculiar scenario was brought up to me when discussing my argument with a student. As stated above, I believe that is a class of things that fits a certain description. [...]
[...] He states that we (those with my intuition) are imagining a potential scenario that is possible, but misidentifying that as a situation where water is not identical to H2O. According to Kripke, while it is impossible for water not to be identical to H2O, it is possible that someone be in a qualitatively indistinguishable situation where their words or do not refer to the same thing. What we would really be doing in the situation we are imagining here, is using the word to refer to something different than what the word in our language actually refers to. [...]
[...] The concern is the following: what if everything that fits the description of water in the actual world is taken to this new planet, and when it arrives it starts to form a poisonous mushroom-like substance. We decide to gather them all back up and bring them back to the actual world, and when we get there they behave like water again. Did water stop being when we took it to that other world, or do we now have to add a description to that is a new discovery but is true of all water-like substances? [...]
[...] Water is not identical to H2O; the reference of is actually the class of things that fits the description of water. It seems that in our current world H2O is the only thing that fits the description, but imagines a scenario where, in some distant future, we discover that all the water in the ocean is XYZ, and not H2O. We need not then make a distinction between H2O and XYZ by naming some of it water, and some of it something new. [...]
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