Philosophy of language has been quite an active field for the past half century or more, and understandably there is considerable overlap between it and philosophy of mind. It is hard to talk about words, sentences, and their meanings without running up against questions about concepts, and how they are created and manipulated in the mind. Likewise, it is hard to ask how the mind works without running into questions about how it manipulates symbols and how the symbols it manipulates may affect its working in turn. We may not think entirely in words, but there seems to be a strong connection between the way we think and the way we articulate.
Philosophy of language went off into the weeds for a while during much of the 20th century. There was a great collective effort to "naturalize" the notions of reference, meaning, and a bunch of others, which effectively means an effort to explain them in reductive materialist terms. This effort strikes me as doomed, because it is a flail in the direction of admitting that there is something mysterious about semantics, while trying to ignore the elephant in the room, namely consciousness.
Moreover, most formal investigations into semantics and meaning are infected with a naive realism about meaning, bordering on Platonism. There often seems to be a pretheoretic assumption that a given term has a True Meaning that we may only perceive partially, with our use of the term muddled by our imperfect sensory apparatus, or limited cognitive abilities, and our incomplete scientific knowledge. It is assumed that, armed with a correct philosophy of language, we would be in a position to determine what any given term really means.
There is no "really means". It makes no sense to speak of the meaning of a term unless you know who is doing the meaning and why. What does the user of the term know or believe about the term? What about the term is important to the user and the user's audience? What is the user trying to accomplish by using the term right now? What sorts of habits and objectives are baked into the speaker's entire notion of how and why they might coin and use terms in the first place? What are the preconditions that would have to hold in order for the user and the audience to be satisfied that the term was being used with only a tolerable amount of ambiguity? Note in particular that these preconditions might differ considerably from those that you might insist upon before you thought the term was being used unambiguously. Nor should we allow the limitations of a given language-using community's scientific knowledge impugn their use of the term, and their idea of what the term means.
People are sloppy with their terminology. Depending on context and audience, they use terms with varying degrees of precision. Some contexts call for more precision, and so people coin new terms. Technical fields are full of specialized jargon for this reason. Sometimes people even use a familiar term in a more restricted sense than most people do sitting around the dinner table. There is something about the phenomenon of language, though, that beguiles investigators into thinking that all language could and should be made infinitely precise. There are urgent and interesting things about language and minds, but on the way to considering those things it seems that few make it past the rocks, lured by the siren call of theories of Platonic infinite precision.
Of central importance to any discussion of language and meaning is the notion of intentionality. Intentionality is the property of being about something else; it is sometimes informally defined as "aboutness". Beliefs, desires, and propositions all have intentionality, rocks and teacups do not. Intentionality is real, it exists as a feature of the universe. There are some things that really are, inherently, about other things. All such things, however, are exclusively in minds. In a purely objective, extrinsic, materialistic world, everything that happens does so strictly according the the laws of physical causation, like so many beer cans perched on fence posts hit with rocks. No matter how many beer cans you have, and no matter how they may be connected (with dental floss, perhaps) there is no inherent sense in which some set of them "come together" to be about another set of them. They just do what they do because they must, each of them blind to all of the others, with no subset of them "representing" other subsets (or anything else for that matter) except insofar as we choose to see them that way with our conscious minds.
Sometimes it is convenient for us to speak and think as if things out there were really about other things (road signs about gas stations, for example), but this is a may-be-seen-as kind of thing, a way of talking about what is, at heart, lots of complex physical interaction. Left on their own, the mechanics of the physical road sign, and its interactions with photons of light, up to the point at which those photons interact with your nervous system, are well understood without recourse to any notions of "reference".
When someone points, they are telling you to do something - look over there. A reference is a pointer, and as such, it is prescriptive, not descriptive. It commands. Even this, though, gives it too much credit. It doesn't actually do anything - it just sits there. It is a lot like an algorithm in this sense, and in fact is a degenerate case of an algorithm. As such, unto itself, it is neither true nor false, it neither represents nor misrepresents, it just does its physical interaction as do all physical things. If intentionality is to be a really-there thing at all, it is a spooky, mysterious, in-the-mind-only kind of thing, like the redness of red. Like redness, it really exists, but in order to account for it properly we will have to overcome our unease at its spooky mysteriousness.
Terms are about things. "Water" refers to, is about, water. "Cat" is about a cat, or cats in general. So far, so good. The stuff out there in the world that a term "picks out", the actual cat(s) or the actual water, is called the extension of the term.
There are aspects of meaning that are not done justice by simply pointing out the extension of a term, however. Often there is, implicit in a term, not just what the term actually refers to, but how it refers to it as well. One of the most well known examples is that of renates and cordates. Renates are creatures that have kidneys, and cordates are those with hearts. As it turns out, everything that has a kidney has a heart, and vice versa. So "renate" and "cordate" both have the same extension; they both refer to exactly the same set of actual animals. Nevertheless, it should be intuitively clear that the terms do not have exactly the same meaning. One can imagine a creature that is a renate but not a cordate, or a cordate without being a renate. The terms "renate" and "cordate" have perfectly distinct meanings, and it seems like an accident of nature that they happen to coextend.
If extension is the actual stuff that a term picks out, intension is how the term picks it out. Intension is the questions a term asks the world before it decides that some aspect or part of the world is denoted by that term or not. (If all this anthropomorphizing terms themselves seems a little suspect to you, rest assured, I couldn't agree more. Bear with me.)
To capture and formalize the idea of intension, philosophers of language have come up with possible worlds scenarios. Renates and cordates are the same creatures in our world, but there are possible worlds in which some renates are not cordates. To put it in mathematical terms, intension is a function of possible worlds to extensions in each world. That is, to nail down a term's intension, you let your imagination range over all possible worlds, and for each possible world you determine what the extension of the term would be in that world. When you are done, you have the original (infinite) set of all possible worlds, and for each one, the extension of the term in that world. The resulting (infinite) set of pairings completely captures the term's intension, which comes much closer to the term's meaning than simply specifying its extension in our world.
This talk of possible worlds has always struck me as a clunky and unnecessarily extravagant way to talk about why we use the terms we use the way we do. Surely when ordinary language users use a term like "renate", infinite sets of possible worlds do not actually play any role in their mental processes. If theories based on possible worlds scenarios are not theories of our mental processes as we learn, interpret, or use terms in everyday life, then what are they theories of? I honestly do not know, but I detect a whiff of Platonism - the faith that semantics is something real (albeit non-physically, or metaphysically real), something we could have theories of, theories that could be objectively right or wrong independent of our mental processes. Be that as it may, if infinite sets of possible worlds seem a bit unwieldy, hold on - it gets worse.
Moreover, talk of possible worlds often seems to assume that picking out the extension of a given term on a particular possible world is unambiguous. It is always admitted that on some worlds, a term just might not have an extension, but on the ones in which it does, there are generally seen to be no real problems picking it out, and there are no real problems telling which are the worlds in which the term has an extension in the first place. All that matters is the final answer: that crisp, neat mapping of possible worlds to extensions that defines the intension.
If possible worlds are interesting fodder for speculation at all, it is because of the ambiguous cases. Are terms defined absolutely, because of some inherent essence of the thing described? Or are terms (and concepts, for that matter) defined relationally, in terms of their functional interactions with other things? Was John Muir right: "When we try to pick out anything by itself, we find it hitched to everything else in the Universe."? To the extent that we admit that our idea of what a thing is depends on its relations to other things (perhaps even, transitively, all other things) any change a possible world exhibits from our own puts the burden of proof on someone who claims that a term is directly transferable from our world to that possible world. Could there really be Pepsi worthy of the name in a world with no Coke? Most people would say "probably", but it gets tricky depending on context.
In how many possible worlds is there an extension of the term "Albert Einstein"? What if there were a world just like our own, but the man we credit with discovering special and general relativity, and who adorns countless dorm room walls, was named Albrecht Eisenstein? What if there were a man named Albert Einstein who was raised exactly as our Einstein, in exactly the same family, with exactly the same genetics, but who made his living as a piano tuner, never entering the world of science at all? What if Albert Einstein discovered relativity, but was a blond Englishman? What if, in addition, his name was Edwin Chillingsworth? In how many of these worlds (and any of the others that we could come up with for hours and hours) can we definitely pick out the extension of the term "Albert Einstein"? It depends on the kind of conversation we are having. Sometimes, even with proper names (the paradigmatic examples of what are called "rigid designators"), we are speaking more abstractly, sometimes less. Moreover, when we speak abstractly, or figuratively, we do not always carry out our abstraction along the same axes, abstracting away the same kinds of details as we might at other times, in different conversations.
Let us imagine, for example, that there is an alliance of advanced civilizations that calls itself the United Federation of Planets. This federation never makes overt contact with a newly developing civilization until that civilization is on the verge of inventing warp drive, which would allow the civilization to explore the cosmos. In the midst of clandestinely monitoring an emerging civilization, a Federation captain might have a conversation with his First Mate in which he asked, "Have they had their Albert Einstein?" This might be a slightly awkward way to phrase the question, but nevertheless it would be reasonably unambiguous, and the First Mate could answer "yes" or "no", perhaps following up with some detail as to the exact state of the civilization's technological development. Obviously, the captain was speaking somewhat abstractly. He did not mean to ask if the civilization had produced a wild-haired, slightly comical man born in 1879 in Ulm, Germany. If the planet being watched was populated with gelatinous green blobs that communicated through their highly developed sense of smell, and had no ears or eyes, the First Mate could still perfectly truthfully answer "yes" to the captain's question. The captain is interested in certain of Einstein's characteristics, but not others.
On the other hand, what if Mileva Einstein (Einstein's first wife) found herself sucked out of our universe through a wormhole and ended up on the bridge of our Federation starship. Once it was clear that she had no hope of ever returning to her own world, she might ask, "Does this world have an Albert Einstein?" She would not take yes for an answer if the Albert Einstein being referred to was a gelatinous green blob that had discovered relativity. She might very well, however, take yes for an answer if the Albert Einstein were our piano tuner. She is also speaking abstractly, but she is abstracting along different lines than the Federation captain is. Both abstractions are perfectly valid, in their respective contexts.
So it is not enough to think that we may speak of something either abstractly or specifically. It is not even enough to see that we may speak more or less abstractly, along a continuum. In different contexts a term may be abstracted along different lines, in a continuum, holding different properties as essential. That is, we cannot even talk about speaking abstractly, even allowing it to be a matter of degree rather than admitting discrete states, unless we know who is doing the abstracting and what their interests are, what they consider essential properties of whatever it is they are talking about, and what they assume their audience will consider essential properties.
Ours is the only world we are forced to deal with, and it quickly becomes clear if someone is flat out using a term to refer to something that other people would not use the term to refer to. But as soon as we enter the realm of possible worlds, we open the door to legitimate disagreements, for a given world, as to what constitutes the extension of a given term. Once we start hypothesizing in this way, it is often by no means obvious whether the extension of a term exists, or exactly what its extension is in a given world. There may be no way, even in principle, of answering these questions absolutely, depending on the context of the usage, and depending on who the speakers and listeners are, and what their interests in communicating are. It is these sorts of inherent ambiguities that possible worlds scenarios should get us talking about, but which most possible worlds thought experiments ignore. One of the most well known such thought experiment is Hillary Putnam's Twin Earth.
In his widely cited paper, "The Meaning of "Meaning"", (1975) Hillary Putnam argues against the sort of internalist characterization of meaning that I argue for. Putnam's most memorable example is a possible world scenario involving a hypothetical Twin Earth. Twin Earth is just like our Earth, perhaps even including a twin me and a twin you, with one exception: on Twin Earth, the substance that they call "water", while drinkable, odorless, transparent, and in all other "superficial" ways identical to our water, is really not made of H2O. It is instead made of some other chemical compound, that Putnam abbreviates as XYZ. The question that presents itself immediately, of course, is whether or not XYZ is really water.
Putnam flatly claims that it is not. If water is H2O, then the extension of the term water is the set of all quantities of H2O, anywhere in the universe that they occur, and nothing else. Anyone who uses the term water in such a way that it has a different extension is simply wrong, or is essentially speaking a different language than English as it is spoken on Earth. Putnam's main point is, as he put it, that "meaning ain't all in the head". My twin and I may be in identical mental states as we use the term water, but we mean different things by virtue of the fact that our respective uses of the term water have different extensions. For Putnam, the meaning of a term depends crucially on its extension.
Putnam also says that before about 1750, no one knew that water was H2O, even though it really was. If it turned out that some, but not all, "water" on Earth was really XYZ, it would thus turn out that people who had referred to quantities of XYZ as water (the pre-1750 people) were wrong all along. Putnam claims that the usage of pre-1750 speakers of the term "water" to denote XYZ would be retroactively invalidated by future scientific discoveries, even though they lived and died in a community of speakers, listeners, and readers who used the term with unanimous and unambiguous (to them) agreement as to its meaning. I find this claim downright bizarre.
Usage is right. Usage wins. All language is folk language. All language is slang.
Water is a cluster concept - a collage of properties, memories, associations, nuances, connotations, descriptions, expectations, and "scripts" or algorithms for dealing with particular types of watery situations. All of the elements of this collage tend to be correlated in our world, so we draw a line around them with a purple crayon and slap a label on them, water, and go about our lives. We don't have to consider the relative importance of the different elements of the collage (in terms of being defining characteristics of the collage) until some clever philosopher comes up with a contrived thought experiment, and asks us to consider the collage if one of its elements were removed or changed.
In Putnam's thought experiment, the element that is swapped out is the fact of water's microphysical constitution, a fact that most of us learned in high school but which has little impact on our day-to-day lives. I suspect that many of our concepts are loose aggregates in this way, and that because their separate components or properties tend to be correlated in our experience, we assume that the entire cluster is much more tightly integrated than it necessarily is.
How many things could turn out to be different about water before you really felt that you could no longer call it "water"? Do you know how heavy water is? What if it were a hair heavier than you thought or a hair lighter? What if it had some magnetic properties you had somehow managed to avoid hearing about until right now? What if you just read that in certain fields, generated in high-energy physics laboratories, water turned orange and viscous? These things might surprise you, but they would hang like Christmas tree ornaments on the core concept "water". Other, more abstract concepts are more tightly integrated in our minds. I would argue, for instance, that there are no superficial properties of the concept "three". There is not a thing you know about the mathematical concept of three that you could change without inarguably wrecking the whole thing. If you change a whisker on three, it just can't possibly be three anymore. Water might glow in the dark, (but only in the southern hemisphere during a lunar eclipse) and possibly still be water, but a number that is exactly like three but not prime just isn't three.
Because we on Earth have only ever been exposed to water as H2O, we have not had to consider the possibility, but perhaps we have a "big tent" concept of water. Maybe water is multiply realizable, like the term building. Buildings, after all, get to be buildings by virtue of their use, their functional characteristics, but can actually be constructed out of a great many things. We think of water as being H2O, because that is the only kind we have run up against, but maybe water made out of XYZ would not phase us.
On the other hand, we have strong intuitions that what something is made of, even if we can't see it and have no direct evidence of it without sophisticated equipment, has a lot of authority in deciding what it really is. So maybe XYZ isn't water after all, and the microphysical constitution element of the collage trumps all the others. I don't know, and neither does Hillary Putnam. The question is a sociological one, not a philosophical one. We could send a colony to Twin Earth, give them full knowledge of the chemical difference between Earth water (H2O) and Twin Earth water (XYZ), and let them go for a generation or two, and check back to see if they call both substances water or if they have come up with another term for the XYZ kind of water. Maybe they all use the term water for both kinds of stuff, but every now and then an annoying pedant among them corrects people, the way some people tend to compulsively point out split infinitives. Maybe both H2O and XYZ get to be called water in everyday conversation, but the scientific journals use some long Latin names for the chemical formulae on those rare occasions when they need to differentiate between the two. However they go, there's your answer.
We cleave our concepts along lines that are important to us. Microphysical constitution is important to us, so it gets a relatively high ranking. We have found it useful or satisfying in some way to let this criterion determine the extension of water. We have been told a very plausible physical story about the world around us, one involving atoms and molecules, and we believe it (for good reason). So when we make distinctions among the things in our world, we tend to give credence to distinctions rooted in this story. The point is that any authority or importance microphysical constitution has in determining whether something is water or not derives from our goals, rules and conveniences, and not from any immutable natural laws or any Platonic Meaning Of "Water".
Saul Kripke, in a series of lectures collected in "Naming and Necessity" (1972) notes that at some point scientists figured out that whales are not fish, and that is really the right way to talk about it. They did not change the standard usage of the words "whale" and "fish"; they corrected the standard usage. Moreover, most reasonable people at the time would quickly acknowledge this, upon being told of the biological details involved. This is because, as Kripke says, an interest in natural kinds was built into the original enterprise of classification. When people coin and use terms, they like to think that they are thereby distinguishing fundamental types. Distinctions made in terms of our current best story about what it means to be a fundamental type are ones we like to formalize in our language. Right now, for most of us, that story is the one about microphysics.
Kripke defends exactly the sort of Platonic understanding of meaning that I argue against here. His main intention is to argue against what he called the Frege/Russell understanding of meaning, which he characterizes as identifying a term with a bundle of descriptive properties. I said above that water is a cluster concept. Kripke says that Frege and Russell would agree, and they would identify "water" with the cluster. That is, to Frege and Russell, the term "water" is just a shorthand for that cluster of properties. A consequence of this, according to Kripke, is that if some of the properties in the cluster turn out to be invalid, the whole term must be thrown out. Kripke's take on Frege/Russell semantics is that the cluster does not have one of those clauses that lawyers stick into contracts saying "even if some clause herein is found to be invalid, the rest of the contract is still in full effect.".
One of Kripke's examples involves gold. One of the properties of gold is that it is a yellow metal. According to Frege/Russell semantics, this is a definitional property of gold: it is one of the things that makes gold gold. What if, due to some highly implausible optical illusion, it turned out that gold was blue, and had been blue all along, but we had only thought it was yellow? Kripke rightly points out that we almost certainly would not say that since gold had been defined (among other things) to be a yellow metal, this new discovery means that gold does not exist, and we have some new blue metal in its place. Rather, we would just say that it turns out we were wrong, and gold is blue, not yellow.
Kripke says that when we link a term to a cluster of properties, we are not identifying the term with the cluster. Rather, we are fixing a reference with the cluster. When we coined the term "gold", we referred right through the superficial properties by which we identified gold, to the actual thing or stuff that (as it were) lay behind those superficial properties. Any of the superficial properties could thus turn out not to be actual properties of the stuff at all, and that would not affect our reference. Stretching the point a bit (but not too much - he produces some pretty compelling examples), Kripke suggests that all of the properties in the cluster could be not real properties of the referent, and the reference would still hold. We may use the cluster of properties to identify the thing referred to, but it is implicitly understood by all users of the term that the properties themselves are somewhat provisional, that the important thing is whatever it is that we (for the moment, anyway) believe possesses the properties. The properties are not the thing itself, but just a way of pointing out the thing.
This is a good example of the Platonism I spoke of earlier. The properties are the shadows on the cave wall, pointing in the direction of the reality that lies behind, or beyond the (mere) superficial cluster of properties. Kripke confronts head-on my claim that the coiners and users of a term ought to have the final say in deciding what counts as being picked out by that term. He illustrates his point using the common example of Hesperus and Phosphorus.
"Hesperus" and "Phosphorus" are the terms the ancient Greeks used to denote the evening star and the morning star, respectively. Although the ancient Greeks (before Pythagoras, anyway) did not know it, both were actually the single object we now call the planet Venus. Kripke says that Hesperus and Phosphorus just are Venus, and always were from the moment the terms were coined. There may be worlds in which Venus does not exist, but there is no possible world in which Hesperus and Phosphorus are different objects from each other, or anything but the planet Venus.
Now I can imagine a possible world in which there are two distinct objects in the sky. Let us call them (with apologies to Dr. Seuss) Thing 1 and Thing 2. I bet I could arrange this world in such a way that if we were to teleport the ancient Greeks to that world, they would accept that Thing 1 is Hesperus and Thing 2 is Phosphorus. We should think long and hard before we say that the Greeks are simply wrong to call them that. They coined the terms, after all, to make distinctions that were important to them in their lives. They lived and died happily in their use of those terms. They used them with perfect (as far as their purposes were concerned) unanimity and specificity as to their meaning. I think that this gives them a fair amount of authority in deciding what the terms mean, and if they decide that Thing 1 is Hesperus and Thing 2 is Phosphorus, you had better make a very good case that they are wrong.
It is not enough to point out that the ancient Greeks' scientific knowledge was wrong or incomplete. That is not what is at issue here. They would probably have changed their terminology if they had figured out that Hesperus and Phosphorus were both Venus. But for now I am interested in the ones that never did know that, and their use of their terms that they invented to make sense of their world as they experienced it and thought about it. They used the terms, and the terms had meaning for them. How did this meaning work?
Kripke says that the Greeks had ways of identifying Hesperus in the sky, and ways of identifying Phosphorus. But these clusters of properties, these ways of identifying them, are not what Hesperus and Phosphorus are, even to them. By coining the terms, the Greeks were fixing a reference to Venus, even though they did not know it at the time. In effect, they referred right through the properties by which they identified Hesperus and Phosphorus, to the actual thing behind them, namely the planet Venus.
Kripke's arguments have some intuitive appeal. But rather than argue about whether the Greeks were really using "Hesperus" as shorthand for a bundle of observed regularities in the sensory input they received from their environment, or they were really fixing a reference to Venus, I'd like to take a step back and ask: on what basis could either claim be right or wrong? By virtue of what, exactly, can Kripke say that the Greeks were fixing a reference rather than identifying a cluster of properties?
When the Greeks used the term "Hesperus", did they thereby instantly pick out something several light-minutes away, and if so, does this process of picking out violate relativity theory by traveling faster than light? Could we verify or disprove Kripke's claims by building a device to detect the invisible meaning rays that connect a user of the term "Hesperus" to Venus? Of course not. Reference is not an actual physical process that happens in the real world. So if reference is not a process of physical causation, what is it? It is nothing. Nothing, that is, except some (admittedly mysterious) stuff happening in the mind. If you hear me use the term "water" (more physical causation, involving vocal chords vibrating, waves of pressure moving through countless air molecules, pushing on an ear drum, etc.) then I induce some stuff to happen in your mind. Some of this mental stuff may include certain "raw feels", expectations, equivalence relations and tests, and who knows what all else. But it is mental stuff, in the mind only.
The only real questions about semantics concern what minds do under the influence of terms, both internally and externally generated. Put another way, once God created all the physical facts of the universe, as well as the facts about consciousness (or, depending on your outlook, including the facts about consciousness), there was no more work for Him to do to create all the facts about reference. Except insofar as it reflects something about how minds work, reference is an explanatorily useless concept. Moreover, I see no reason to think that it constitutes any kind of phenomenon in need of explanation beyond straightforward physical causation (except, again, insofar as it is a product of conscious minds, in which case it is very much in need of explanation, as are all conscious phenomena). So if reference is not a physical phenomenon, and does not even supervene on physical phenomena (reference travels faster than light, after all), and reference is explanatorily useless and does not itself constitute an explanandum worthy of the name, how is it that anyone could have a theory of reference that they claimed was "right", and that other theories were "wrong"?
What does Kripke himself cite as the final authority to back up his claims about fixing references? He produces some good examples (like the blue gold described above) that incline us to think that his claim about "fixing a reference" accords with our intuitions about the way reference ought to work. Is this enough to convince us that reference really does work that way, though? Ultimately, Kripke seems to think that his particular Platonic notion of reference goes through because we want it to. Perhaps it isn't so much the case that Kripke does not think that this Platonism is objectively true of the universe, but rather that it holds true because all language users are Platonists at heart. As Kripke puts it, a desire to classify things into categories of natural kinds was built into the original enterprise of language use. We all go about our lives knowing that whatever clusters of properties we use to identify things are somewhat ad hoc, and subject to revision if we come across evidence that the underlying reality is different than what we thought it was.
When phrased this way, assuming I haven't misunderstood and/or misrepresented Kripke, his arguments are not so different than mine. This reference-fixing, the Platonism, is not an actual feature of the universe, it is a fact about how our minds work, and our needs and desires with regard to language construction. We want to classify the world in certain ways, so we build that imperative into our notions of reference. The final authority for deciding that water is really H2O, then, is our goals and intentions in using language in the first place, and that's why the Greeks were really referring to Venus even though they didn't know it.
Unfortunately, I think this charitable reading does misrepresent Kripke. While he does talk about our desire to classify things in a certain way, it is pretty clear from the absolute way in which he phrases his claims that he thinks of reference as a really-there, actual fact of the universe sort of thing, in a robustly externalist way. It is necessary that Hesperus is Venus, and it is necessary that water is H2O, and the Greeks would be wrong to call my Thing 1 Hesperus, not because of caveats and codicils they had written into their original charter establishing the goals and rules of their particular linguistic enterprise, but simply because they would be absolutely, objectively wrong, and that's that. He would strongly disagree, I think, with my claim that questions about reference are sociological or psychological, not philosophical ones.
Extension is the stuff in the universe that a term "picks out". Of course, terms do no such thing. With apologies to the National Rifle Association, terms don't pick things out, people do. Extension seems like a reassuringly concrete idea: the extension of the concept of water is a set of actual molecules out there in the actual world. But extension is not so clear cut. Putnam allows that determining extension requires an equivalence relation. We can not specify all the occurrences of water on Earth without having a way of saying "all the stuff that is equivalent to this stuff here in this glass". This equivalence relation, the criteria we use to decide if something is water or not in various real or imaginary scenarios, is the intension. Extension is supposedly concrete, while intension is rather more abstract (remember that intension is a function that maps possible worlds to extensions on those worlds).
But you can't get to the extension without going through the intension. Thus extension is itself something of an abstraction: we can never, in practice, enumerate all the molecules of water in the universe, so we can never actually pick out the extension of the concept of water. We are always at a certain remove from anything's extension; all we really have at our immediate disposal is intension. All we can really do is talk about the general kinds of things we would consider water. What we really are talking about when we use the term the extension of water is a bunch of tests we can apply to different situations, ways of applying some equivalence relation. Importantly, we apply those tests, we pick out the water. By itself, a term just sits there.
How do we know about water's microphysical constitution, anyway? Most of us simply read it in a book or were told it in school and accept it. Some of us ran tests with instruments. Originally, sometime after 1750, someone ran such tests, and inferred the microphysical constitution of water from the results of those tests. But the results themselves, the raw data, are functional properties of water, facts about how water behaves in different circumstances. These sorts of properties are no different in kind than the results of the "tests" I run when I smell water, dip my hand in it, taste it, etc. The fact that in one case the instrumentation involved was built by people, and in the other case the instrumentation consists of devices I was born with (tongue, fingers, eyes, etc.) does not make any difference in terms of the type of property of water we are talking about. For the Twin Earth thought experiment to go through, there must be at least some "superficial properties" of H2O and XYZ that differ. Otherwise, how would any scientist ever have told the difference? At some point, if you feed H2O into a mass spectrometer you get one result, and if you feed XYZ in, you get a different result. Different raw data equals different "superficial properties", just as much as if H2O and XYZ tasted different. The microphysical constitution that Putnam regards as the absolute determinant of true wateriness, is a story that we inferred from various different superficial properties. It is literally incoherent to speculate that XYZ and H2O do not differ in at least some "superficial" properties.
Now I happen to like that story. It is remarkably powerful and parsimonious in its ability to link all kinds of phenomena in the world, confer cognitive power upon us, organize our mental economy efficiently, and ultimately, help us invent microwave ovens and rocket ships and all sorts of other things. But it is not the only imaginable story.
We should steer clear of the assumption that the pre-1750 people used their rough and ready conception of water only provisionally, and that they were waiting for science to tell them about water's microstructure so they could be more precise. Pre-1750 people, whether or not they had ever heard of Aristotle, were basically Aristotelians. They already knew the elemental constituents of water - namely water. Water was simply one of the basic kinds of stuff their world was made of, and most people didn't question whether or not water might be made of anything still more basic. Their understanding of science was wrong, but their ability to refer was working just fine.
What if there were a prescientific tribe of people somewhere that had two words for water. Water referred to the water from the river, that brought life and was good and blessed by the gods, but shwater referred to the evil water from the spring that was cursed. No explaining that water was chemically identical to shwater would make them change. Microphysical constitution is just an unimportant property to them compared to the essential goodness or evil of the water/shwater. The goodness or evil determines what the substance "really is". Perhaps they are not prescientific, and they understand about chemistry and H2O, but still hold their religious beliefs, with full acceptance that there is no empirical basis for them. They have chosen a different property, a different element of the collage to define the essential nature of water/shwater.
Lore has it that the Eskimos have 100 words for snow (the actual number seems to vary a lot depending on where you read this old chestnut). Let us imagine that one of their 100 words is spelled and pronounced exactly like our word "snow". This is like the situation with the pre-1750 people calling both XYZ and H2O "water", only with us playing the part of the pre-1750 people, riding roughshod over what to others (the Eskimos in this case) are important distinctions. We aren't right and the Eskimos aren't right. We all just make the distinctions that are important for us to make, and we don't waste time coining a lot of extra terms to allow us to split hairs we don't have to split. A term is only as precise - can be only as precise - as is necessary to make the discriminations of interest to the community of users of the term. How narrowly or broadly I define my terms is something I (or my culture) decide in the interests of setting up my conceptual and linguistic pallatte in such a way as to get the maximum cognitive or communicative bang for the buck. There is no right or wrong answer as to the narrowness or breadth of my definition of the term "water".
There is some stuff out there in the world (water), and our interactions with it have lead us to attribute some "superficial" properties to it. We also have a story in our minds, an explanatory framework that we have found to be very useful (our current physical theories about atoms and molecules and such). Some of this stuff's superficial properties have lead us to infer that it fits comfortably into a particular place within this explanatory framework. The success of a particular scientific theory or another does not absolutely (and retroactively!) determine meaning. Whenever we have a collage of data (superficial properties), we infer a story to bind it all together. The story is the purple crayon we use to demark the collage. It is this story that we cling to as the determinant of meaning, the crucial defining characteristic of each of our concepts. It determines the equivalence relation, the intension, that in turn determines our tests for inclusion in or exclusion from the extension. This story, and thus meaning itself, is in the head.
I suppose someone could still insist, for the sake of the argument, on hypothesizing a substance that behaved exactly like H2O as far as current science was able to determine, but which really was not H2O. I could take the standard cop-out that people sometimes take with thought experiments and demand details. I guarantee that no one could possibly specify such a situation at any satisfying level of granularity. But the standard cop-out would lose a larger and more important point. It is in principle, literally nonsensical to speak of something that behaved exactly like H2O, and wasn't really H2O. As I and lots of others have pointed out, science doesn't really claim, at heart, to tell us what is really going on out there in the world. It only specifies a bare schema, a circularly defined pattern of functional dynamics, but it is silent about what is doing all that functional interacting. To act exactly like an electron is to be an electron. There is no such thing, by definition, in principle, as something that acts exactly like an electron but really isn't an electron. By the same token, there is no way something could behave exactly like H2O but somehow not be H2O.
When it comes right down to it, our relationship to the outside world is entirely functional. That is, we know everything we know about the world because of the world's dispositional properties, its behavior. Water is as water does. There simply is no essense of water that does not manifest itself functionally, at least none we could ever know, even in principle. Any time we speak of reference with regard to something out there, we are talking about reference to a bundle of functional dispositions. This is functionalism turned on its head: it is not the mind that must be understood in functionalist terms, but the world.
The main point here is that the story about molecules and such, the explanatory framework, is entirely in our heads (although there is a strong likelihood that there are things out there whose dynamics map nicely to this framework). We can not say what anything "really is" beyond where it fits into our explanatory frameworks based on its observed "superficial" properties, which is to say, based on certain sensory experiences we have had. Speculation to the contrary is the kind of pursuit that gives philosophy a bad name.
So what is going on in our minds when we use the term "water", either saying it, hearing it, or thinking it? That is the $64,000 question. A very interesting question, yes, but a question about what is going on in here, in the mind, and not a question about any notion of "meaning" beyond that. I have characterized the concept of water as a cluster, a collage, but I have said that it involves equivalence relations or tests we apply to situations, and that it is delimited by a story that we infer from experience. Obviously this all needs a lot of clarification. Do I even have one single thing in my mind that I can call my concept of water? Does it, strictly speaking, have a fixed identity that persists over time? If so, how much of it can you change before you must call it a different concept altogether? Do concepts subsume other concepts? What part do qualia, the what-its-likeness of water's wetness, its (lack of) taste, etc., play in all of this? How much relative weight does Kripke's project of language use (that of dividing things into categories of natural kinds) have? These are the truly interesting questions about the limits of the meaning of the term "water", but these are all straightforwardly questions about minds. There is a lot of stuff going on in our heads and it will take considerable work to sort it all out.
One thing we can speak of with confidence, however, is the relationship between all this mysterious stuff happening in our heads and the outside world. We do not directly perceive matter. There is a long, twisty causal chain that links certain events that happen in the physical world with percepts and concepts in the mind. Or perhaps more suggestively, our concepts and percepts are constrained or influenced by these events. Until we understand the concepts in our heads better, the details of the influence of the external events upon them will remain murky.
I say events rather than matter because as far as the causal influences on the mind are concerned, matter only manifests itself in the form of particular events - photons bouncing off objects, being refracted by a lens, striking rods and cones in the retina, kicking off a whole series of neural firings, etc. No two people are ever subject to the same series of such events. "Matter" and "the external world" are just a hypothesis we come up with to account for the largest number of these events in the greatest detail, subject to whatever as-yet improperly understood cognitive limitations there may be. Over the course of my life so far, I have had a huge number of sensory experiences. Some of these experiences have lead me to infer the existence of something called "Great Britain". My concept of Great Britain is a hypothesis I have formed, one that makes sense of a lot of particular sensory experiences (whatever "makes sense of" turns out to mean). It may well be an overwhelmingly plausible hypothesis, but a hypothesis it is nevertheless, formed under the physical causal influence of my senses.
Note that none of this makes any claims as to the similarity or difference between the stuff happening in my head and the stuff happening in yours or anybody else's. There may be a great deal of variation possible among the possible concepts of water (or Great Britain) in peoples' heads, as long as whatever the different concepts are, they allow for an appropriate correspondence or mapping between matter in the world (or the events by which matter impinges upon us) and our linguistic behavior.
So where does that leave us and our term "water" and our associated concept of water? We have 1) molecules of stuff somewhere out there in the world in our rivers and streams. These molecules, as we encounter them, cause physical events to occur, which cause still other events, etc. until some event(s) in this chain ultimately impinge in some way upon 2) some mysterious things happening in our heads; and finally we have 3) our observable linguistic behavior, which presumably is caused or influenced by 2). We have a long way to go before we understand 2) and the exact relationship between it and 1) and 3), but once we do understand these things, there will be nothing left to explain about language and meaning.
It is sometimes said that meaning is merely mediated by causal connections between the outside world and our minds. I, however, would say that meaning just is those causal connections, plus some mysterious stuff happening entirely within the mind. Any talk of meaning beyond this has no explanatory or predictive power at all. There simply are no facts about the universe, either extrinsic, third-person "scientific" facts, or subjective phenomenal what-its-like-to-see-red-type facts, that are explained by assuming invisible magic meaning rays connecting our thoughts to trees, cars, and the Milky Way galaxy. The causal chain between physical events that happen in the world and the concepts we form in our minds may get very complex, but it is still just billiard balls knocking together. There is no other kind of connection between the stuff out there and our concepts in here. The problem with the term "extension" is that it strongly inclines us to believe that there is. It presumes a sort of spooky mystical connection between the collection of molecules of H2O in the universe and our internal concept of water. There is no such connection.
If you ask me as an English speaker if XYZ counts as water, I may think for a moment or two then give you my opinion, which I made up just then. I may then give you arguments for my opinion, that you may or may not accept. My opinion may or may not be in accord with that of the majority of the rest of my linguistic community. It may or may not even be in accord with the dictionary definition of the term "water". But my answer is still just something I made up. Of course, that is what all language ever is - at some point, someone just makes stuff up, and other people adopt it in their speech. If, on the other hand, you ask me as a philosopher if XYZ really counts as water, I'm afraid I would have to ask you to rephrase the question, because as stated it is too loaded with presuppositions to admit a yes/no answer.
I would like to emphasize, though, that my deference to usage is not a sort of black-box behaviorism, or functionalism. Usage is not strictly inter-personal; a great deal of our usage of terms takes place entirely between our own ears. We use language not only to communicate with one another, but to think. In stressing usage I am not trying to equate meaning strictly with observable linguistic behavior, but also with the cognitive use we make of words and expressions, and the ways in which terms are related to concepts in our minds.
Sometimes the notion of modes of presentation is invoked to solve semantic problems. The idea is that Lois Lane knows that Superman can fly. Yet it would surprise her greatly to discover that Clark Kent can fly. But Clark Kent and Superman are one and the same person (that is, the term "Superman" and the term "Clark Kent" have the same extension), so in some sense the claim that Superman can fly and Clark Kent can fly should convey exactly the same information. They both make the same claim about the same individual. To resolve the apparent conflict, it is argued that any given claim must be understood under the proper mode of presentation. Superman and Clark Kent may in fact be the same collection of molecules, but facts about them are subject to their mode of presentation.
I find talk of modes of presentation very fishy. As far as I can tell, attributing any explanatory power to modes of presentation is just a way of covering for incomplete or incorrect information. Lois Lane knows that Superman can fly but would be surprised to find that Clark Kent can fly because she walks around with an erroneous model of reality in her head in which Superman and Clark Kent are two distinct individuals. She has drawn incorrect inferences about the world. She has, in fact, been deliberately and systematically deceived by the individual who is both Superman and Clark Kent.
In the same way, sometimes you read about Pierre, who has read that London is a beautiful city, one he would like to visit one day, but who once had to take a business trip to an awful, drab and smoggy place called Londres. We are told that Pierre has been exposed to the same city in two different modes of presentation. I prefer to say that Pierre's model of the world is simply wrong. He thinks there are two cities, and bases his expectations, desires, beliefs, etc. on this incorrect model of the world. Maybe someday he will correct the mismatch between his internal model and external reality, maybe not. Either way, there is nothing deeply mysterious about any of this.
Any problems in thinking about these situations stem directly from the intuition of the invisible magic meaning rays that connect our thoughts and references with the outside world - the idea that reference is exclusively or even primarily some kind of instantaneous connection between something in our thoughts (or Lois Lane's thoughts) and the outside world. I do not know exactly what reference is or how it works, but if it is to have a precise meaning at all in the sense of being philosophically interesting or useful, it must be defined as a relationship of some kind between thoughts. Lois Lane's term "Superman" refers to a Superman concept in Lois's mind. There is nothing problematic in saying that for Lois, the claim that Superman can fly and the claim and Clark Kent can fly convey very different information because for Lois, the concept "Superman" is simply a different concept than the concept "Clark Kent". She formed both concepts by drawing inferences from lots of perceptual experiences she had. The concepts then contribute to her expectations of the kinds of perceptual experiences she is going to have in the future.
An idea closely related to that of the invisible meaning rays and Platonic Meaning is that of the content of our thoughts. Many writers use the term with confidence that it has meaning, then go on to spend a lot of effort trying to analyze it and figure out what the content of our thoughts is, or whether content is narrow (dependent on one's internal state) or broad (dependent on one's state plus the state of the world). It always seems to go without saying that there is some fact of the matter. The content of a thought is a lot like the extension of a word. It is whatever the thought is "about". I find the term at best to be a strong pretheoretic nudge in a particular direction, and at worst grossly misleading.
I may have a box. If I put a cake in the box, then the cake constitutes the contents of the box. I could have put the cake in a different box, in which case that other box would have had the same contents that this box now has. Or I could have put some old newspapers in the box, in which case the same box would have different contents. The box is blank, empty, until I put some contents into it. These are the sorts of images and relationships we drag into play as soon as we invoke the highly loaded term "content". I have thoughts, that is all. As far as I can tell, I have no separate "contents" of those thoughts.
Two Dimensional Semantics is getting a lot of attention these days. Chalmers has been writing about it, as have other people. The motivation for 2D semantics is the opinion that intension alone, characterized in the possible-worlds sense, does not quite capture meaning. Specifically, there are terms whose intension is the same (i.e. the terms pick out the same extension in all possible worlds), but that seem as though they have different meanings anyway. I'll hand the mic over to Chalmers here:
According to Kripke, there are many statements that are knowable only empirically, but which are true in all possible worlds. For example, it is an empirical discovery that Hesperus is Phosphorus, but there is no possible world in which Hesperus is not Phosphorus (or vice versa), as both Hesperus and Phosphorus are identical to the planet Venus in all possible worlds. If so, then "Hesperus" and "Phosphorus" have the same intension (one that picks out the planet Venus in all possible worlds), even though the two terms are cognitively distinct. The same goes for pairs of terms such as "water" and "H2O": it is an empirical discovery that water is H2O, but according to Kripke, both "water" and "H2O" have the same intension (picking out H2O in all possible worlds).
So Kripke's claim as paraphrased by Chalmers is that because we now know that they are both just Venus, Hesperus and Phosphorus both must pick out Venus in all possible worlds, and so have the same intension (same extension in all possible worlds = same intension). Yet most people would agree that "Hesperus" does not quite mean exactly the same thing as "Phosphorus". To accommodate this in our theory of semantics, the following reasoning is invoked. Because of the way our actual world turned out, Hesperus is Phosphorus is Venus, and this must hold true across all possible hypothetical worlds. But if we imagine for a moment that our actual world had turned out differently, and in our actual world Hesperus was a different object than Phosphorus, and then we let our imagination range across all possible worlds, we might come up with a different intension for each world so considered. So essentially we set up a grid: first, along one axis (say, the vertical axis), we lay out all possible worlds, and imagine that for each of them, that is the way our actual, real world might have turned out. Then for each of those, we do the old-school possible worlds exercise, considering each possible world as hypothetical (along the second axis, the horizontal one) given that the possible world on the first axis is being considered as actual.
2D semantics is motivated by the Platonic impulse: the certainty that what something "turned out" to be in our actual world somehow fixes its meaning absolutely for all time and in all contexts. Thus, in order even to toy with the idea that things might have "turned out" differently in our world, we have to add a whole new dimension to our already infinite array of possible worlds. So instead of simply (!) considering infinite possible worlds, you consider infinite possible worlds for each possible world, with the possible world on the vertical axis imagined as the way the actual world "turned out". If possible worlds scenarios are clunky, then 2D semantics is clunkiness squared.
Does anybody imagine that when a little kid learns a new term, say "Mommy", that kid constructs a two-dimensional array in her head and fills in all the spaces in that array with the appropriate intensions and extensions of "Mommy" in all possible worlds as demanded by two-dimensional semantics? No - no one thinks this. So if two-dimensional semantics is not a theory of what actual language users do when they acquire and use terms in the real world, what is it a theory of, exactly? The same question could be asked of many theories of semantics. If two-dimensional semantics is the answer, what was the question?
The whole point of needing a second axis (i.e. the second dimension) in 2D semantics is that in our world, renates all turned out to be cordates. Hesperus and Phosphorus both turned out to be Venus, and water turned out to be H2O. We may imagine possible worlds in which things could have "turned out" differently. This phrasing is misleading in that it draws a sharp distinction between a "superficial" acquaintance with the concept of water on one hand, and what water "turned out to be" on the other. Water has not turned out to be anything. We could still find out all kinds of things about water that would surprise us. I could be in the Matrix with a cable jacked into the back of my neck, in a "real" world in which physics is completely different, and in which there is nothing remotely resembling water. Perhaps in prescientific times, peoples' conception of water underwent revisions along the way, before people figured out about atoms and molecules.
We have a set of empirically-derived properties of water on one hand (oderlessness, transparency, etc.) and another set of empirically-derived properties on the other (inferred microphysical constitution), and these two sets of properties have always seemed to coextend in our world. When we let them float free of each other in our imagination, we have to decide for the first time which set gets to keep the tag "water", like a judge deciding which of a divorcing couple gets to keep the house. Because there are two sets of properties, we need two axes in our n-dimensional grid, hence two-dimensional semantics. There could be any number of sets of empirically-derived properties of water, however, so the number two is arbitrary. We actually would need as many axes in our infinite grid of possible worlds as we can come up with logically independent sets of empirically-derived properties.
Imagine a stone-age people who had a word, "pog" that meant, to them, "tool or weapon". As time went on, and the civilization advanced, the same term, "pog", might come to mean more specifically "pointed stick used as a weapon". Later still, it might mean "spear made of ash". Would it be right, then, to characterize the situation by saying that "pog" turned out to mean a spear made of ash, and that really had meant a spear made of ash all along? That the stone-agers who called a rock a pog turned out to be wrong? Would anything interesting be revealed about what meaning is or how it works by hypothesizing a Twin Earth in which the inhabitants used the word "pog" to refer to spears made of birch?
I have a model of reality in my mind (I am not hereby endorsing any particular theory about how we represent reality, much as this seems to imply the existence of some sort of database or something - I am using "model" very loosely). My memories and sensory experiences are somehow more or less integrated into this model, and the model gives me some predictive and/or explanatory powers as I move about in my world. As I experience more, the model changes. My knowledge about the world is always expanding, and I often acquire new facts and new perspectives that make me think of things I thought I knew well in a new way. In real life, concepts do not float free, then one day "turn out". They are always turning out; they never stop turning out.
A pre-1750 person, say Isaac Newton, had a significantly different model of reality in his head, but he had experiences and memories similar to mine, and he fit his experiences and memories into his model. In both our cases, "water" is defined, at least in part, relationally - in terms of where it fits in the reality-model relative to lots of the model's other elements. But my concept of water has certain associations within my reality-model that Newton's does not have, associations that further constrain the concept. There are fewer possible universes that contain stuff I would agree was water than there are for Newton (assuming that I buy into the idea that water is and must be only H2O). I prefer my model of reality to Newton's. I like the neatness, the power, the integrity, etc. of my scientific picture of the world. But in terms of what is going on when we refer, water has not "turned out to be" anything. Newton and I have different reality models, with different constraints upon the universe. Based on our different models, our concepts of water have different satisfaction criteria.
This is not oops-my-brains-just-fell-out relativism. I like science. I believe in science. Atoms are real. Newton was ignorant. But it is a strange form of scientific hubris to build Newton's ignorance of our science into a theory of reference, or to reify the distinction between "prescientific" notions of water, Hesperus, or anything else on the one hand and the way things "turned out to be", or the way they "really are", on the other, and to imagine that this alleged distinction tells us anything interesting about meaning. Just because a cathedral is made of stones, it does not follow that my concept of a cathedral is made of my concept of stones, and just because water is made of H2O, it does not follow that my concept of water is made of my concept of H2O.
The external world seems to fit nicely into a certain type of reductive framework. As we try to figure out how concepts and terms behave in our minds, we should not assume that they are arranged in a sort of hierarchy that matches the structure that our science tells us that the outside world exhibits. Any discrepancies between my internal model of reality and the outside world may interfere with my ability to reach efficacious conclusions, and may limit my ability to communicate effectively with other people, but such discrepancies do not automatically invalidate my ability to refer.
Terms never do "turn out": while sometimes we do discover big important things about stuff we thought we already understood pretty well, the process of turning out is unfolding all the time, and is never finished. We never resolve symbols "all the way down". A possible exception to this might be things that are defined as part of a self-contained system in which everything is circularly defined explicitly in terms of other things within the system, as in mathematics. But even then, we may still discover new truths and untruths within the system that reflect back on our original basic terms.
Consider my car. I have an abstract notion of my car in my mind, and one might think that it maps straightforwardly to some specific collection of molecules, and that this mapping pretty much resolves the notion of my car all the way down. But is the gasoline in the tank part of the car? If not, then there are situations, not all that far-fetched, in which I might have access to my car, all of my car, but be unable to drive it, and this would surprise me. On the other hand, if the gas is part of the car, its molecules are constantly being spit out the tail pipe, and I periodically put new ones in the tank. Which incarnation of my car am I invoking each time I refer to my car? Is the air in all the hoses and ducts and manifolds part of the car? How about all the other fluids, that the car needs to run but which pretty much stay put (unlike the gasoline), but which still need to be replaced occasionally? Are the oil filter and the air filter parts of the car? How about the after-market floor mats? And what can we make of the car collector who claims to have replaced all of the parts of his vintage 1950's convertible, but still thinks of it as the same car he bought at a junk yard ten years ago? What collection of atoms constitutes the car?
All of these questions go away if we accept that we humans deal with vagueness all the time, easily and naturally. When I speak of my car, I'm not talking about a collection of molecules. I'm talking about whatever it is that roughly, more or less, conforms to my notion of my car. Vagueness is easy. It is precision that takes effort. You have to think carefully and hard to give consistent answers to the questions above about exactly what does and what does not constitute the extension of my term "my car". You may, after some thought, be able to answer the questions in a way that satisfies you, but only after effort and creativity on your part. In expending this effort, you would not be telling the truth about your pre-existing concept of my car, but rather you would be making up answers in response to this novel challenge. You might easily have gone to your grave without ever having answered those questions, and without even ever realizing that the questions existed to be answered, and this is perfectly fine. It is much easier to live with the ambiguity and not even notice it. It strikes me as backwards that some philosophers of language write chapters in books about The Problem Of Vagueness. We don't have to resolve the term "my car" all the way down, so we never do. "My car" has not, and never will, turn out to be one single, unambiguously specifiable collection of matter.
The mathematical notion of symbol evaluation is partially to blame for the bias philosophers have for this idea of "turning out". In algebra, you can have a variable, x, that everyone can see is a variable. It can be manipulated as a variable, but at some point, you may resolve it, by substituting a number, like 43, for it. There is an unambiguous, explicit delineation between the variable before it was resolved, and the value it has afterwards. There is a universally understood sense in which x is unresolved, and exactly what aspects of it obey certain mathematical rules anyway, and what aspects of it are left unspecified.
In real life, as we generate and parse natural language, things are almost never that neat. Symbol evaluation in natural language is not an either/or kind of thing, as it can be in mathematics. For most of the terms we use in daily life, there are various degrees of specificity of resolution, and we resolve terms or inhibit their resolution to the appropriate degree, and in the appropriate order according to all kinds of rules of context as we string terms together in our thoughts or utterances. Modern semantic theory posits a very sharp distinction between a term's intension and its extension. The trouble is, rigidity of designation, to use the philosophical term, is a sliding scale. Parsing and generating language is less like symbol resolution as traditionally conceived than it is like tuning a complicated musical instrument.
In certain contexts in computer science, the term "binding" is used to describe symbol resolution: a variable expression is "bound" to a particular value, and thus ceases to be a variable. Furthermore, there is an idea of "early binding" and "late binding" of variable expressions. The idea is that you can have a variable, and you can resolve it right away (early binding), then feed it into other calculations, or you can let it exist as a variable in those calculations, then resolve it to a specific value at the end (late binding). Sometimes you can get very different results depending on when you do your variable bindings.
Some of the sense of this can be illustrated with the slightly awkward sentence, "By the year 2050, the president of the USA will be a woman." The likely intent here corresponds to late binding of the term "the president of the USA". We let that term float in the abstract as we evaluate the sentence, knowing that it will not be resolved until 2050. Or we could bind it early: as I write this, the president of the USA is Barack Obama, so the term "the president of the USA" resolves immediately to "Barack Obama", and the sentence then states that by the year 2050, Barack Obama will be a woman, a considerably less likely claim. Different terms seem to call for earlier or later binding, more or less specific resolution depending on context (which, of course, is made of other terms, which need to be resolved as well).
A great deal of the jargon associated with philosophy of semantics can be recast in terms of early vs. late binding. To me, this is often clearer and more intuitive. When Kripke speaks of fixing a reference as opposed to identifying a term with a cluster of properties, he is talking about early binding as opposed to late binding. When the Greeks coined the term "Hesperus", they bound it early (if unknowingly) to the actual thing, Venus (at least, that's what Kripke thinks). Kripke attributes to Frege and Russell the counterclaim that it is OK to bind terms late, and that the Greeks let the properties float free of any binding, so there could be a possible world in which Hesperus is something other than Venus. If the "superficial properties" are the x, and Venus is the 43, Kripke says that as soon as the Greeks said x, they immediately meant 43 even if they didn't know it. Frege and Russell, on the other hand, say that it is fine to let x stand in its own right, and we could perfectly meaningfully find out later that x is 43, or 23, or 101.
Another example is one that William Lycan cites in his introductory book "Philosophy of Language" (2008): "I wish that her husband weren't her husband." In the first instance of the term "her husband", it is early bound, and picks out an actual guy, but the latter instance of "her husband", it is late bound (or rather, not bound at all within the sentence, but still waiting to be bound by the time the sentence ends). In its late bound state, the term is allowed to persist as an abstract specification, as binding criteria for some future binding to an actual person.
This distinction between early and late binding is really what motivated 2D semantics. In ordinary 1D semantics, with only a single infinite array of possible worlds to consider, you bind your terms early, according to what they mean in our actual world. This early binding corresponds to what is sometimes called a term's secondary intension. So water's secondary intension is H2O, for example. Then, once that meaning is fixed, you let your imagination range over all possible worlds, picking out the extension on those worlds (i.e. the H2O on each world). This, at least, is how Kripke characterized it in his objection to 1D semantics that Chalmers paraphrased above. But in 2D semantics, you allow for some late binding as you consider possible worlds. In the first part of the 2D semantics exercise, when you are considering each possible world as actual, you let some more abstract version of the term float over all possible worlds, and do your binding in each imaginary possible world, then with the meaning so fixed, let your imagination range over all possible worlds. This is sometimes called the primary intension of a term. While water's secondary intension is H2O in all possible worlds in the 1D semantics case (we bound it early, in our actual world), water's primary intension is H2O in our world, but XYZ in Putnam's Twin Earth (we bind the abstract specification - the watery stuff - to the actual extension late: after we've switched our attention to the hypothetical XYZ world, i.e. considered it as "actual").
It is assumed that there is no ambiguity in deciding what aspects of a given term should be allowed to float free across possible worlds to be bound by the contingencies of each one, and what aspects are constant across all worlds, both considered as actual and as considered as counterfactual. That is, which aspects of water are to be considered part of the abstract characterization (e.g. its odorlessness), and which aspects are the actual essence that the "superficial" properties "turn out" to be (e.g. water's microphysical constitution). It is also assumed that there is the abstract characterization (unbound) of a term, and the actual extension (bound), and none but those two completely discrete states. That is, you have the variable, the x (the watery stuff in the environment) and the value it resolves to (H2O or XYZ). It is really a form of scientism or math envy among philosophers that causes them to shoehorn reference into the binary symbol resolution model. The "superficial" properties of water (clear, odorless, liquid, etc.) are the x, and it was an unresolved variable for eons, as we humans ignorantly used the term "water" not knowing what it really was. Then our scientists figured it out, and now we know that water "turned out" to be H2O! We found the answer - x is 43!
But early and late are relative terms. Moreover, the whole notion of binding, no matter how early or late, is really the same thing as symbol resolution, and subject to the same problems. How narrowly do we construe or intend terms? How figuratively are we speaking or interpreting a term at a given moment? What aspects of a concept do we consider fair game to abstract away and what aspects do we hold constant as we do our figurative construing? In the Twin Earth thought experiment, it was taken as a given that water's "superficial properties" were to be held constant, and its microphysical constitution could be abstracted away as we considered different scenarios. But in real life, the narrowness or broadness of construal of a term, and the aspects of a concept we choose to hold constant and the aspects we feel free to abstract away, and exactly when we bind our terms to specific extensions ("resolve" a more abstract characterization of a term to a more specific extension) can vary wildly, often along a continuum, and are highly context-dependent, even within a single sentence.
A tautology is an expression of the form x = x. Since x is always equal to x, regardless of what x actually is, tautologies (in theory) convey no information about x or anything else. A fancy way philosophers have of saying this is that tautologies have no "semantic content", and thus (in theory) have no meaning. But as with so many aspects of language, theory and reality do not always line up. Let me indulge here in a bit of fiction.
Jimmy and Frankie grew up together in the same working class neighborhood. In their pre-teens they stole hubcaps together, then later whole cars. Soon enough they hooked up with the mob and worked together. Some years go by, and their bosses become aware that Jimmy is skimming a little off the top each month. As a test of loyalty, they send Frankie after him. Frankie has no trouble cornering his old friend, and in the ensuing confrontation, Jimmy pleads, "Frankie, its me, Jimmy. I've always been there for you, Frankie, more times than I can count. This can't be the end, Frankie. Not like this. I know I screwed up, I screwed up bad. And you know I'll make it up, Frankie, you know I will. Come on, Frankie, please!" Frankie says nothing for a moment, just looks at Jimmy with his expressionless unblinking eyes. Then he quietly says, "Business is business, Jimmy."
Or how about this conversation:
"Every time I think about the holocaust, it shocks me all over again. You'd think that after hearing and reading about it all these years, I'd be jaded, or numbed, but no. I still can't get my head around the enormity of it, the reality of it."
"Hey, what happened, happened."
"What do you mean? It wasn't just something that happened. Real people did it! A government staffed by human beings coolly presided over the deaths of millions!"
"People are people."
"How can you say that? Killing six million Jews is not normal human behavior!"
"Well, you know, Jews are Jews after all."
"You jerk! What kind of a Nazi are you, anyway?!"
Then there is always the trendy "It is what it is." Along the same lines, there is the saying that by the time you are thirty, you must accept that no one is your mother, not even your mother.
For poor Jimmy, the supposedly information-free tautology is literally a matter of life and death. The point here is that these are not particularly special cases. People talk like this all the time. They convey lots of information in ways that a logician would say is impossible. The uses of the terms in these tautologies are perfectly valid, and must be accounted for by any theory of meaning. In these tautologies, the same term is interpreted narrowly or broadly, bound earlier or later, considered abstractly or specifically in different ways and to different degrees depending on its use in different places within the same sentence. The meanings of the terms in question are determined on a case by case basis, on sliding scales. Dictionaries seduce us into thinking that there is a discrete number of meanings any term can take on. To be sure, there are some stakes in the ground, but between these stakes there is often a continuum of meaning, and people slide up and down that continuum so effortlessly that they almost do not notice it.
In modern usage, the word "quick" means fast. When Shakespeare referred to the quick and the dead, he meant "alive". It may well be that in Elizabethan times, that was a common sense of the word "quick", one that has fallen out of favor. But to our ears, it is a poetic turn of phrase, a case of Shakespeare speaking figuratively. This figurative sense of the word "quick" plays off of its more restricted sense, and makes sense to us. It is just a broadening of the term. How broadly or narrowly we use terms is in constant flux, and highly context dependent. There is no distinct line we cross when we use a term to mean one thing, but take liberties with its breadth, and when we use a different sense of the term.
The other day on the highway I saw a flatbed truck carrying an enormous underground water tank. Obviously the tank was not underground, yet you probably never thought of the term "underground" as referring to a type before. You probably always thought that it must mean literally, under the ground. We very often, perhaps almost all the time, do not speak literally. Am I speaking figuratively, metaphorically, then, when I mention the underground oil tank when it wasn't underground at all? Well kind of, I guess, but no, not exactly.
Most people are perfectly comfortable using a term figuratively in one breath, and literally in the next, to varying degrees depending on all kinds of variables. Ambiguity lurks everywhere. Determined and ingenious people can tie themselves into knots, finding ambiguity just about anywhere they look hard enough. No one seems to have a problem with this except philosophers, a fact that does not speak well of philosophers.
I have already argued that to a reductive materialist, the fundamental things of which the universe is made are unimaginably blind, stupid, and amnesiac. There are no relations between them except causal ones. Moreover, causal relations are instantaneous, and are "forgotten" immediately. Once a particle nudges another, the second particle careens in a new direction. Was just nudged a moment ago, or a hundred years ago? Or was it simply always careening in this direction? It, of course, has no idea. Hypothetical causal interactions, functional dispositions, a whole pile of maybes, are nothing but imaginary clouds: counterfactuals don't count (as I have also argued before.)
The only real relations, standing relations that persist through time, are qualitative. In particular, there is no room for the relation of reference in such a blind, stupid, billiard ball universe. Reference is phenomenological. There is more to qualitative consciousness than seeing red.
My strictly internalist construal of intentionality and meaning may seem counterintuitive or flat-out wrong. A naive realist about meaning might say, "Look, there's a lawn mower. Its really there, you can touch it. It isn't a hypothesis or an inference, and when I think about it or talk about it, I'm thinking and talking about it, period." When I call the lawn mower a concept I have formed from lots of sensory experiences, and when I say that my thoughts about the lawn mower are really thoughts about that concept in my head, and not truly about the actual, physical, out-there-in-the-world lawn mower, this sounds at best like a needlessly indirect and awkward way of characterizing the situation.
Perhaps, but is there a good way to decide really and actually whose is the right way to think about reference? What empirical result could ever decide the issue? What rides on the outcome? What possible objective difference could it make who is right and who is wrong? If the answer is that there really is no difference, then right there we have a concession that there is no real, objective thing called "meaning" that exists between a concept or perception in my mind and a lawn mower. No invisible magic meaning rays beam from my forehead to the lawn mower. It comes down to a choice of how we want to characterize the terms "meaning" and "intentionality", and (to my mind) a trade-off between a desire to respect our pre-theoretical intuitions and a desire to carve Nature at the joints, as the slightly grisly cliche says. We should feel free to define terms in such a way as to facilitate clear and fruitful analysis going forward. This is one of those situations in which the philosophical latitude to define terms any way we want, and then go on to prove all kinds of things on the basis of those definitions has lead generations of epistemologists to build castles in the air. As we define (or perhaps more loosely, merely characterize) our terms, when given the choice between respecting our intuitions and common usage on one hand, and zeroing in on a potentially unique phenomenon in the universe on the other, I prefer the latter.
Now I will continue, in my everyday life, to speak about things in the outside world. "About" is a perfectly good colloquial English word, and from a very early age we all use it as if it darn well is a connection between our minds and the outside world (I have thoughts, desires, etc. about stuff out there in the world), and even between some things in the outside world (like molecules of ink on paper) and other things in the outside world (like fire hydrants). I am just saying that the use of the term in this way does not reveal anything about how the universe works. If you are interested (as I am) in reference as something that is really there, at work in the universe and not just one of those may-be-seen-as kinds of things, then you are forced to the admittedly indirect internalist characterization of intentionality and meaning. The externalist take on meaning will always be reducible to other stuff, and in itself is as explanatorily useless as the luminiferous ether. When construed externistically, meaning becomes a largely sociological question, and not something all that amenable to philosophical analysis. Colloquially, perhaps meaning ain't all in the head, but if it is of any interest to a philosopher, meaning has to do with the way some thoughts relate to other thoughts.
The only respectable way of construing meaning externalistically that I can see is to take meaning as really just a shorthand way of talking about an unwieldy amount of physical causation, plus some mental stuff. For my current purposes, it is the mental stuff that I would like to zero in on and figure out, and I do think that "reference" and "intentionality" and "meaning" entail some unique and interesting mental happenings, above and beyond the redness of red. Like seeing red, these mental phenomena are actual, fundamental facts of the universe, and are worth exploring. I believe that this is an important part of the puzzle of the mind, the part that will allow us to put what it's like to see red together with what it means to think in the same big picture. Clinging to the naive realist position, with its invisible magic meaning rays just serves to obscure what is really interesting about these phenomena, and to postpone serious inquiry into them.