Now broadcasting from the desert

I have not posted in a long time -- I've been busy with my move from Pittsburgh to Las Vegas, and with all the craziness that attends moving cross-country and starting your life over. But we are starting to settle in, so blogging may pick up again soon.

Several months ago, Doug Patterson asked me if I could contribute something to a volume he's editing for OUP called Alfred Tarski: Philosophical Background, Development, and Influence. I was honored, since many of the other contributors breathe rarified logico-philosophical air, so I cobbled an article together out of various bits of my dissertation. I now have a draft of the paper, boringly entitled "Tarski's Nominalism," and I would greatly appreciate any and all feedback from interested readers. To help you determine whether you are an 'interested reader,' I've cut-and-pasted a bit of the intro:
"This essay aims to answer three related questions about Tarski's self-described 'nominalism with a materialistic taint' through an examination of Carnap’s 1941 dictation notes. First, what is Tarski’s view? Second, what are the rationales for his view? Finally, how does Tarski attempt to reconcile his nominalist philosophical scruples with mathematics, since mathematics deals with paradigmatically abstract objects, such as numbers and sets, whose rejection is a standard sine qua non of modern nominalism?"

As a brand-new Pitt HPS alumnus, I wanted to sing the praises of a couple members of the incoming class. First, Jonah Schupbach, of Berkeley, Bacon, & Bird blog-fame, just had a paper published in Philosophy of Science on one of my favorite topics, the evidential and explanatory role of unification in science. And Jason Byron (nee Baker) has written an article, forthcoming in BJPS, that argues for a point that I became convinced of while doing work for my dissertation. Just to get a sense for what the logical empiricists were thinking about in 1940, I flipped through a few journals from the 1930s that they were reading and publishing in, especially Erkenntnis and Synthese. I was very surprised to find that there were lots of articles on philosophical details related to biology -- some of them dealing rather closely with the science. This was surprising because the usual story among current philosophers of biology is that philosophy of science completely (or almost completely) ignored biology until the late 60s. Jason has now done the detailed spade-work needed to substantiate that impression I had.

Semantics and necessary truth

I have recently been reading, with great profit, Jason Stanley's draft manuscript Philosophy of Language in the Twentieth Century, forthcoming in the Routledge Guide to Twentieth Century Philosophy. The paper's synoptic scope matches the ambitious title.

I'm curious about one relatively small claim Jason makes. On MS p.17, he says:

intuitively an instance of Tarski's schema T [GF-A: '...' is a true sentence if and only iff ...] such as (7) is not a necessary truth at all:
(7) "Bill Clinton is smart" is a true sentence if and only if Bill Clinton is smart.
(7) is not a necessary truth, because "Bill Clinton is smart" could have meant something other than it does. For example, "is smart" could have expressed the property of being from Mars, in which case (7) would be false.

This certainly has (as Stanley says) an "intuitive" ring. But now I'm not sure it's correct.

Here's my worry: as a preliminary, recall (as Tarski taught us) that semantic vocabulary should always be indexed to a particular language -- e.g., we must say 'is a true sentence of English' or 'x refers to y in Farsi' etc. in the full statement of sentences like (7). But then I am not so sure that such sentences are not true in all possible worlds. Is it really the case that, in English, "is smart" could have expressed the property of being from Mars? We specify a particular language (in part) by specifying the semantic values of the words of that language (at least, if we are not proceeding purely formally/ proof-theoretically). Wouldn't we be speaking another language at that point, that was similar to English, but not the same?

My intuitions lean towards saying that this would not be English, but those intuitions aren't firm. I think the question boils down to: "Is 'English' a rigid designator (i.e., does 'English' refer to the same thing(s) in all possible worlds)?", but I'm not sure about that, either. Which way do your intuitions run?

Tarski, Quine, and logical truth

The following must have been addressed already in the literature, but I'm going to mention it anyway--perhaps a better-informed reader can point me in the direction of the relevant research. W.V.O. Quine offers the following characterization of logical truth:

The logical truths are those true sentences which involve only logical words essentially. What this means is that any other words, though they may also occur in a logical truth (as witness 'Brutus,' 'kill,' and 'Caesar' in 'Brutus killed or did not kill Caesar'), can be varied at will without engendering falsity. ("Carnap and Logical Truth," §2)

All I wanted to mention here is that Alfred Tarski had already shown, in 1936's "On the Concept of Logical Consequence," that Quine's characterization is a necessary condition for a sentence to be a logical truth, but not a sufficient one. For example, if one is using an impoverished language that (i) only has proper names for things over five feet tall, and (ii) only has predicates applying only to things over five feet tall, then the sentence 'George W. Bush is over five feet tall' will be a logical truth -- because no matter what name from this impoverished language we substitute for 'George W. Bush' or what predicate we substitute for 'over 5 feet tall' in this sentence, the resulting sentence will be true.

Now some historical questions: did Quine think his condition was sufficient, or just necessary? (I quickly checked "Truth by Convention," and I didn't find any conclusive evidence that he considered it sufficient.) If Quine does consider this a proper definition of logical truth, how does he/ would he answer Tarski's objection? -- and/or why doesn't Quine simply adopt Tarski's definition of logical truth, viz. 'truth in all models'?

(You might think Tarski's objection shouldn't count for much, since I used a very contrived language to make the point against Quine. In Tarski's defense, however, (a) assuming that every object has a name in our language also seems somewhat artificial, and (b) Tarski proved (elsewhere) that a single language cannot contain names for all (sets of) real numbers (See "On Definable Sets of Real Numbers," reprinted in Logic, Semantics, Metamathematics).)