Hisham asked:

Kripke says if a substance is not H2O then it is not water, regardless of the substance's phenomenal
properties. My question: What if H2O has the phenomenal properties of blackness and hardness
instead of transparency and fluidity? Is it not possible for H2O to have those properties? If it is, in
what sense is the statement, "Water [transparency, fluidity, etc.] = H2O" necessary?

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You seem to have stepped into the middle of what is actually a long and complex debate about the
nature of essences, of terminology, and of counterfactuals, to name but a few of the issues here. The
"earth" and "alternate earth" arguments have to do with the nature of our definitions of things; whether
they refer to actual things, to our uses of things, to social constructs, etc. If a substance has the
formula H2O, is transparent, etc., and we call it "water", why are we calling it "water"? Because of
appearance? Because we drink it? Because it has a particular physical makeup (H2O)? Suppose
there were an alternate earth where people drank something that behaved like H2O but had a
different formula, but was in every other way (never mind laws of chemistry, suppose they were
different there) like H2O. Should it be called "water"? Suppose on that alternate earth the substance
with the formula H2O was indeed hard and black, and undrinkable. Should it be called "water"? This
question has not been answered to everyone's satisfaction, and a great deal of the bias toward
different answers depends on what you think the function and nature of language is. Does language
describe the world? Does it express only our beliefs? Only social conventions? What if it does a bit of
all of those... then to what does "water" refer? Well. Do some more reading on this; it's not a simple
issue. Go look up the "alternate earth" debates.

Steven Ravett Brown

Kripke holds that water is H2O in all possible worlds, that is, that necessarily water=H2O. Hence,
when we ask 'is x water?' we disregard the phenomenal and functional properties of x and instead
focus on its chemical make up. If x is not made up from H2O then x is not water. Hence, the truth
condition for 'x is water' is ''x is water' is true if and only if x is H2O'. Saying water=H2O turns out to be
equivalent to saying H2O=H2O. Now, you argue that a substance could be H2O and lack all the
phenomenal and functional properties of water, and that this would be that the substance wouldn't be
water. However, consider ice. Ice lacks the phenomenal and functional properties of water (its hard, it
doesn't fall from the sky when it rains) but is still H2O. Does this mean that ice is not water? In a
sense yes, but in another no. Kripke is just going to argue that H2O is water under certain conditions,
like below freezing point. Hence, H2O is necessarily water given certain conditions, like temperature
as in the ice case. The important point is that anything that is in the extension of water (set of all
things that term is true of) is going to be H2O. Maybe the converse needs a few conditions to specify
when H2O is water and not ice but that seems no big hurdle — Everything that is H2O is potentially
water, necessarily.

On a personal note, I find it hard to accept Kripke's position. For example, I doubt very much that I
mean 'can I have a glass of H2O?' when I ask the waiter for some water. Secondly, I doubt whether
the biblical writers cared at all whether the rivers of babylon were filled with H2O or XYZ. I don't think
we use language in the way Kripke suggests. Lastly, I am dubious about the notion of a natural kind
as it is used in Naming and Necessity.Perry wrote a good article on this topic. I can't remember the
title but if you type 'natural kinds' and 'Perry' into the 'Philosophers Index' (search Google) you'll be
able to get the reference.

Rich Woodward

We have made the empirical discovery that the structure of the clear fluid that we call water is H2O. It
is a matter of empirical fact, or necessity in this world that this is so. We could have called black hard
stuff "water" since a classifying word is contingent, but were we to find that the black hard stuff was
H2O that would become an identity relation of empirical necessity. It is conceivable, though not
naturally possible, that we might suddenly come across black hard stuff and find that that, as well as
the clear fluid was H2O, but we wouldn't call it "water" since it wouldn't be of any help in our talk
about two things with such different phenomenal properties which would have quite different uses.
We would use a different name but that name would also be identical to H2O. However, that H2O
should have different phenomenal properties than the ones it has is a logical and metaphysical
possibility, not a natural possibility. In the world as it is, H2O just is clear fluid.

Rachel Browne