3/29/2007

Carnap on what's 'really wrong with the Aufbau'

When I was going through some of the photocopied material I have from the Rudolf Carnap archive, I found the following interesting (to me) remark. Carnap is discussing with Nelson Goodman a draft of Goodman's dissertation (A Study of Qualities, which much later became The Structure of Appearance). Goodman points out various supposed technical defects with Carnap's method of quasi-analysis presented in the Aufbau, and Carnap says roughly the following:

The real problem with my Aufbau is not the various counter-examples that can be constructed against my particular version of quasi-analysis (which I already knew about), but rather the assumption of extensionality.

(I haven't quoted, because I don't think it's allowed.) I like this because (a) it's a really smart philosopher saying 'My book rests on a mistake,' and (b) it fits with my pet theory that the real break between Carnap and Quine stems in large part from Carnap moving away from the extensional languages he espoused in Logical Syntax, while Quine held fast to the extensional standard throughout his life (see the posthumous "Confessions of a Confirmed Extensionalist").

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3/15/2007

confusion and prokaryotes

One of my recurrent interests is confusion, especially in science. The way I understand this concept is as follows: a term or concept is confused = that term or concept takes 2 or more entities to be one entity (where 'entity' covers individual objects, properties, relations, etc.). In other words, a confused concept or term conflates distinct things. I think the phenomenon of confusion is important in science because part of what happens in many scientific revolutions is that, from the point of view of the new scientific framework, the old scientific framework is confused -- or vice versa. (Re: 'vice versa': Einstein's principle of equivalence, for example, would be seen as an unjustified conflation from the viewpoint of a classical physicist: gravitation and inertia are two separate things, and running them together as Einstein does is an unjustified conflation.)

I've recently started looking at another potential case of confusion in science, but I'm a bit uncertain about it, and would like to air it to get reactions.

In high-school biology class, we are told that the highest/ most basic division among life on Earth is between 2 kingdoms: prokaryotes and eukaryotes. Eukaryotes are all those organisms whose genetic material is encapsulated within a nucleus; Prokaryotes are organisms whose genetic material is not. In other words, Prokaryote=df not-Eukaryote.

However, in the last 2-3 decades, the highest taxonomic level has slowly switched to a three-group classification: Eukaryotes, Archaebacteria, and (Eu)bacteria. Why? The short answer is: "on the molecular level, [archaebacteria] resemble other procaryotes, the eubacteria, no more (probably less) than they do the eukaryotes" (C. Woese et al., PNAS 1990 p.4577).

The upshot for present purposes is that there are actually two distinct highest taxa whose genetic material is not enclosed within a nucleus, viz. the archaebacteria and the eubacteria. From this point of view, it appears that 'prokaryote' conflates the archaebacteria and the eubacteria. But if we recall the earlier characterization of 'prokaryote' as simply 'not-eukaryote,' then 'prokaryote' does not appear to be a confused term. So the question is: Is 'prokaryote' confused, or not? (And why?) I'm happy to hear just intuitions, as well as intuitions backed up with some sort of argument or evidence.

P.s. -- For some readers, this discussion will immediately call to mind Quine's solution to the 'grue' paradox in his paper "Natural Kinds" (in Ontological Relativity and other essays). There, Quine notes that if the predicate P picks out a natural kind, then not-P usually doesn't. A hackneyed example: 'gold' picks out a natural kind (any matter with atomic number 79), but 'not-gold' does not, because it covers many, many completely disparate things -- there are too many ways to be not gold for 'not-gold' to refer to a natural kind.

This might make us think that many/ most predicates of the form not-P are, in fact, confused, since such predicates most often apply to many different natural kinds. All I can say at this point is: that sounds counterintuitive to me... it doesn't feel to me like 'not-gold' conflates distinct things.

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3/02/2007

Scott Soames' "Actually" in Vegas

One of my favorite philosophers, Scott Soames, was in Vegas last weekend; he gave a great talk entitled "Actually", and he and his wife Martha took a trip with some of the folks in my department out to the beautiful Valley of Fire state park.

One of the main points Soames pushed was that "actually" plays two very different roles in philosophical semantics. 'Actually p', spoken in a given world W1, means 'p is true in world W1' (sorry, I can't do corner-quotes in Blogger). Now, Soames says there are two ways to specify this world W1:
(1) by picking it out purely indexically, in the way 'I' picks out the speaker of the token, 'now' picks out the moment of utterance, etc. -- so on this way, 'actually p' means 'p is true in THIS world' (or '...in OUR world').

(2) by (roughly- see Soames' paper for the gory details) giving the proposition associated with the Carnapian state-description of W1. (A state-description assigns a value of true or false to every atomic sentence in a language.)

Scott pointed out that if we pick out world W1 in the second way, then 'Actually p' is a priori: once you have a state-description of the world in which that sentence is uttered, then you have all the information you need to figure out its truth-value. This runs contra the conventional wisdom that says 'Actually p' is a posteriori, since we only learn whether p is true in this world via experience; Soames's point was that 'Actually p' is learned via experience when we use way (1) of picking out the world W1, but since there is this other way (2), 'Actually p' is in fact knowABLE a priori, if not knowN a priori in practical cases.

This is very clever, and I need to think more about it, but I think my esteemed colleague James Woodbridge had the best question/ objection of the afternoon. He said 'Actually p' does not just mean 'p is true at world W1,' but rather 'p is true at W1 AND W1 is actual/ instantiated.' Someone could give me the entire state-description of the world we currently inhabit, and then I could calculate from that description that p is true in a world satisfying such a description -- but I still wouldn't know that 'Actually p' is true, because I wouldn't know that the state-description matched this world. (And I was too slow on the uptake to grasp Soames's reply to James.)

My favorite part of Soames's whole talk, though, was the following approximate quotation:
"Perhaps the contingent a priori is just an old wives' tale."
I know I can't get my grandmother to stop talking about Kripke...

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