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January 22, 2005



Thanks for the report Dave. It's useful to have an official precis of where you and Frank diverge.


Yes, very interesting comments.

Isn't another important difference between you and Frank Jackson that his (two kinds of) intensions are semantic values for public languages, constituted by linguistic conventions, whereas your intensions are defined epistemically for individual speakers, largely independent of a larger community and its conventions?

It seems to me that this is the main difference at least between your two-dimensionalism and that of Lewis (e.g. in Plurality, pp.40-50, where 1-intensions are called "truth-conditions" and 2-intensions are unnamed functions from worlds to truth values). And I always thought Jackson was very close to Lewis in this respect.


Well, Frank certainly allows that the A-intension associated with an expression (especially a name) can vary between speakers in a community, so I don't know if there's a big difference here. (I'm not sure about Lewis, as I don't have my copy of Plurality handy.) Also, note that while I define primary intensions in terms of an expression's epistemic role for a speaker, it may be that for many expressions (though probably not for names) the epistemic role associated with competent use is itself determined by linguistic convention, so merely having a constitutive tie to individual epistemic role doesn't entail independence from linguistic convention.

Re your trackback comment (which I'll comment on here to avoid fragmentation): yes, it looks like your interpretation was closer to the mark than I thought at the time. After the talk, though, Frank resisted the claim that he was reducing A-intensions to C-intensions (saying that he thinks that if anything A-intensions are more fundamental): rather I think he sees both as grounded in a single "true at a world" relation (maybe defined only over "one-dimensional" expressions?). Certainly he doesn't think that the relevant descriptions have to be expressible by more basic expressions in the speaker's vocabulary -- the description (or perhaps better, the property/relation?) might just be tacitly grasped. Of course this raises questions about what constitutes this tacit grasp. If it's constituted by some sort of disposition to apply a term in specific cases, then the difference with my version won't be as great as it initially appeared to be. But maybe there is a stronger relation involved.


I hope this is not too much of a digression (in that case, simply ignore it, and receive my apologies) but I was never quite able to grasp Frank Jackson's new position on consciousness.

From what I gather, he rejects Type B materialism in such a way that no change of position based on "practical" epistemological issues such as the Paradox Of Phenomenal Judgement (that is, that it's very, very unlikely for a phenomenal judgement to be correct if we accept epiphenomenalism) can make him accept it.
Does that mean he became a Type A materialist?

That seems almost impossible for someone who used to be a dualist. Perhaps only possible (psychologically and intellectually possible for a person, not philosophically possible) if one accepts some kind of very, very strong "Cognitive Illusion" view.


Yes, Frank is now a type-A materialist, embracing Lewis-style analytic functionalism and the ability reply to the knowledge argument. He thinks that representationalism (and diaphanousness) make this conclusion easier to accept, as the properties that Mary seems to "learn" about are merely represented properties rather than instantiated properties. But a "cognitive illusion" is definitely involved -- hence the title of his paper "Mind and Illusion".

N.B. The excellent new collection There's Something About Mary: Essays on Phenomenal Consciousness and Frank Jackson's Knowledge Argument (MIT Press, edited by Ludlow, Nagasawa, and Stoljar) collects all of his papers on the knowledge argument as well as a lot of papers by others.


What's the difference between a primary intension and an A-intension? Is it just terminology?


Interesting. Did he say whether the domain of the single "true at a world" relation consists of centered or un-centered worlds?

If the description isn't a real linguistic description, but something like a function from (centered) worlds to individuals, I don't see how talk about sentences S and S' and dropping "actually" can be applied. In fact, doesn't rigidification go with a loss of information? The property of being the teacher of Aristotle and the property of being the author of Nicomachean Ethics, when rigidified, both become the property of being Aristotle, the constant function from worlds to Aristotle. So there is no way back from the rigidified function to its de-rigidification.


Matt: To a first approximation it's just terminology (Jackson and I may have slightly different views of the intensions, but the difference in names doesn't really mark the difference in views). There's a long history of multiple names for two-dimensional semantic values. The antecedents are Kaplan's "character" and Stalnaker's "diagonal proposition", but one can't use these terms here as they stand for subtly different sorts of entity. In my 1993 Ph.D. thesis I used "prior" and "posterior" intension, but I wasn't wild about these terms. For my 1996 book I thought a lot about the best terminology, and even polled a number of colleagues about options. A significant majority voted for "primary" and "secondary" -- including Frank Jackson! But for his 1998 book he introduced the new terms "A-intension" and "C-intension", I think on the grounds that they were more mnemonic. I've also occasionally used "epistemic" and "subjunctive" intension when specificity about the foundational notions is required.

Not long before he died, I received a letter from David Lewis urging me to stay with "primary" and "secondary" on the grounds that these terms were by far the most likely to catch on. I've come to think that David was right about this, and this seems to be the way that the literature is going. So I'll probably mostly use "primary" and "secondary" in future.


Wo: Frank didn't say what was in the domain, but I presume it was uncentered worlds. Maybe one could handle indexical cases by putting an indexical-laden expression E into the form 'the entity that actually bears F to me' (where F is a one-dimensional expression for an appropriate relation), and then saying that 'E is phi' is true at a centered world W considered as actual when 'the entity that bears F to S is phi' is true (simpliciter) at the uncentered world W' corresponding to W, where S is a one-dimensional expression that when evaluated at W', picks out the individual at the center of W. If 'now' or other indexicals are involved, one can generalize this pattern in the obvious way.

If there's no actual linguistic expression F available, presumably one will do things in terms of the underlying relation. The idea might be something like: we have antecedent reason to believe that for all names N, there is a relation R such that the name functions to rigidly designate whatever actual entity bears R to the speaker. Then one can say that 'N is phi' is true at centered world W considered as actual iff (in the uncentered world corresponding to W) the entity that bears R to the individual at the center of W has the property denoted by 'phi'. Strictly speaking this doesn't appeal to a second sentence S', but there's still a broad sense in which this proposal defines truth at a world considered as actual in terms of truth at a world simpliciter. I don't think that the fact that rigidification involves a loss of information makes a difference here.

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