[hist-analytic] Kripke and Contiingently Necessary Truth!?

Bruce Aune aune at philos.umass.edu
Fri Nov 6 08:05:38 EST 2009


I am not sure what to say about Steve’s proposed counter example to  
Kripke’s identity statement, “heat = molecular motion.”  Kripke’s idea  
was that if in all circumstances in which we apply the commonsense  
term ‘heat’ a certain kind of molecular motion is taking place and  
vice versa, then we may justifiably assert that heat is that kind of  
molecular motion.  Kripke offered no scientific details, and I doubt  
that he is committed to the idea that micro-processes in question  
involve one kind of micro process rather than another—molecules, say,  
rather than ions.  (From what I remember of organic chemistry, it  
might be true that molecular interactions are always ionic reactions,  
H2O being, for instance, an aggregate of H3O+ and OH- ions.)

But Steve’s example does bring to mind a difficulty with the alleged  
identities involving common sense and theoretical concepts, a  
difficulty that has always made me doubt the truth of such identities  
as water and H2O. The difficulty is that the various substances picked  
out by “water” do not have any single micro-analysis. As I expressed  
the point in chapter 5 of my book:

“No one supposes that a homogeneous substance actually fills all our  
lakes, ponds, and streams or that the liquids in those different  
geographical sites are chemically identical. Although we have very  
good reason to believe that any water we drink, swim in, or sail on  
consists largely of H2O, our normal means of identifying a sample of  
water does not depend on this belief or on any other chemical lore. A  
chemist can tell us what proportion of a given liquid is H2O or what  
other compounds it contains, but the deci sion to apply the label  
“water” to the liquid in the Cuyahoga river (which once caught fire),  
the Campus Pond at my university (which is often black and murky owing  
to the presence of thousands of migrating aquatic birds), the Dead Sea  
(which is heavily saline), or a highly diluted gallon of what was once  
Chardonnay wine, will not depend on such a person’s deci sion. In  
fact, if our acid rain began to contain substantial amounts of the  
chemicals mak ing up the XYZ liquid that fills the rivers and ponds of  
Putnam’s Twin Earth without any significant effects on its ability to  
quench the thirst of animals or contribute to the growth of familiar  
plants, ordinary people would call it “water” without hesitation and  
continue to do so if, owing to some extraordinary natural change, it  
became pure XYZ. These and comparable other facts make it evident, I  
believe, that a meaningful reference to water does not depend,  
conceptually or semantically, on any set proportion of actual H2O in  
the liquid a normal person is thinking of. A person with a smattering  
of chemistry might, of course, conceive of water as H2O, but this  
conception would be anomalous in practice, for no water most persons  
have ever drunk is close to being pure H2O. Good drinking water is  
heav ily dependent on its mineral content.”

Best regards,
Bruce
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