Read Darwin's Dangerous Idea Online
Authors: Daniel C. Dennett
advances in the detecting transducers. At some point, such escalation of Words, according to Humpty Dumpty, get their meanings from us, but engineering would reach diminishing returns, for there is no such thing as a whence do we get meaning? What exercises Fodor and these other philos-foolproof mechanism. In the meantime, the engineers and users are wise to ophers is a concern for
real
meaning as opposed to
ersatz
meaning,
"in-make do with standard, rudimentary two-bitsers, since it is not cost-effective
trinsic"
or
"original"
intentionality as opposed to
derived
intentionality. Well to protect oneself against negligible abuses.
might Fodor want to ridicule the idea of organisms as artifacts, for it provides The only tiling that makes the device a quarter-detector rather than a slug-the perspective from which the central flaw in his view, a flaw shared by the detector or a quarter-or-slug-detector is the environment of shared intentions views of the five others, can be exposed by a thought experiment.3
of the artifacts designers, builders, owners—its users, in short. It is only in Consider a soft-drink vending machine, designed and built in the United the context of those users and their intentions that we can single out some of States, and equipped with a standard transducer device for accepting and the occasions of state
Q
as "veridical" and others as "mistaken." It is only rejecting U.S. quarters. Let's call such a device a "two-bitser." Normally, relative to that context of intentions that we could justify calling the device a when a quarter is inserted into a two-bitser, it goes into a state, call it
Q,
two-bitser in the first place.
which "means" (note the scare-quotes) "I perceive/accept a genuine U.S.
I take it that so far I have Fodor, Putnam, Searle, Kripke, Burge, and quarter now." Such two-bitsers are quite "clever" and "sophisticated." (More Dretske nodding their agreement: that's just how it is with such artifacts; this scare-quotes; the thought experiment begins with the assumption that this is a textbook case of
derived
intentionality, laid bare. Such an artifact has no sort of intentionality is
not
the real thing, and ends by exposing the
intrinsic
intentionality at all. And so it embarrasses no one to admit that a embarrassments such an assumption entails.) Two-bitsers are hardly fool particular two-bitser, straight from the American factory and with "Model A proof, however; they do "make mistakes." To say the same thing unmeta-Two-Bitser" stamped right on it, might be installed on a Panamanian soft-phorically, sometimes they go into state
Q
when a slug or other foreign drink machine, where it proceeded to earn its keep as an accepter and rejecter object is inserted in them, and sometimes they reject perfectly legal quar-of quarter-balboas, legal tender in Panama, and easily distinguished from ters—they fail to go into state
Q
when they are supposed to. No doubt there U.S. quarters by the design and writing stamped on them, but not by their are detectable patterns in the cases of "misperception." No doubt at least weight, thickness, diameter, or material composition. (I'm not making this some of the cases of "misidentification" could be predicted by someone with up. I have it on excellent authority—Albert Erler of the Flying Eagle Shoppe, enough knowledge of the relevant laws of physics and design param-Rare Coins—that Panamanian quarter-balboas minted between 1966 and 1984 are indistinguishable from U.S. quarters by standard vending machines.
Small wonder, since they were struck from U.S. quarter stock in American mints. And—to satisfy the curious, although it is strictly irrelevant to the example—the exchange rate when last I checked for quarter-balboas was 2. Read Fodor for amusement, and for insight into a dislike of Darwin's dangerous idea so deep that it overrides the standard practice of attempting to find a sympathetic reading indeed 8.25.)
of texts. His misrepresentation of Millikan is particularly egregious, and is not to be Such a two-bitser, whisked off to Panama, would still normally go into a trusted at all, but can be readily cured by reading Millikan herself.
certain physical state—the state with the physical features by which we used 3. As usual, the issues are more complicated than 1 can show here; for all the gory details, to identify state
Q
—whenever a U.S. quarter, an object of kind
K,
or a see Dennett 1987b, ch. 8, from which this thought experiment is drawn, and Dennett Panamanian quarter-balboa is inserted in it, but now a different set of such 1990b, 1991c, 1991e, 1992.
occasions count as the mistakes. In the new environment, U.S. quarters 406 THE EVOLUTION OF MEANINGS
The Quest for Real Meaning
407
count as slugs, as inducers of error, misperception, misrepresentation, just as balboas? (We could go on adding complications and variations, if it might much as objects of kind
K
do. After all, back in the United States a make a difference to our intuitions. Should it?)
Panamanian quarter-balboa is a kind of slug.
One thing is clear: there is absolutely nothing
intrinsic
about the two-bitser Once our two-bitser is resident in Panama, should we say that the state we considered narrowly all by itself (and its internal operations) that would used to call
Q
still occurs? The physical state in which the device "accepts"
distinguish it from a genuine q-balber, made to order on commission from coins still occurs, but should we now say that we should identify it as the Panamanian government. What must make the difference, of course, is
"realizing" a new state—call it
QB
instead? At what point would we be whether it was
selected for
its capacity to detect quarter-balboas (agreeing entitled to say that the meaning, or the function, of this physical state of the with Millikan 1984). If it was so selected (by its new owners, in the simplest two-bitser had shifted? Well, there is considerable freedom—not to say case), then even if they forget to reset the counter, its maiden move is the boredom—about what we should say, since after all a two-bitser is just an veridical acceptance of a quarter-balboa. "It works!" its new owners might artifact; talking about its perceptions and misperceptions, its veridical and exclaim delightedly. If, on the other hand, the two-bitser were sent to Panama nonveridical states—its intentionality, in short—is "just metaphor." The two-by mistake, or arrived by sheer coincidence, then its maiden move would bitser's internal state, call it what you like, doesn't
really
(originally, mean nothing, though it might soon come to be appreciated by those in the intrinsically) mean either "U.S. quarter here now" or "Panamanian quarter-vicinity for its power to tell quarter-balboas from the indigenous slugs, in balboa here now." It doesn't
really
mean anything. That's what Fodor, Put-which case it could come to function as a q-balber in the fullest meaning of nam, Searle, Kripke, Burge, and Dretske (
inter alia
) would insist.
that term, via a less official route. This, by the way, already makes a problem The two-bitser was originally designed to be a detector of U.S. quarters.
for Searle's view that only artifacts can have functions, and those are the That was its "proper function" ( Millikan 1984 ) and, quite literally, its
raison
functions its creators endow it with by their very special mental acts of
d'etre.
No one would have bothered bringing it into existence had this creation. The original designers of the two-bitser may have been entirely purpose not occurred to them. This historic fact licenses a way of speaking: oblivious of some later use to which it was opportunistically exapted, so their we may call the thing a two-bitser, a thing whose function is to detect intentions count for nothing. And the new selectors may also fail to
formulate
quarters, so that
relative to that function
we can identify both its veridical any specific intentions—they may just fall into the habit of relying on the states and its errors.
two-bitser for some handy function, unaware of the act of unconscious This would not prevent the two-bitser from being wrested from its original exaptation they are jointly executing. Recall that Darwin, in
Origin,
already niche and pressed (exapted) into new service—whatever new purpose the drew attention to unconscious selection of traits in domestic animals; laws of physics permit and circumstances favor. It could be used as a K-unconscious selection of traits in artifacts is no stretch at all; it is rather a detector, or a slug-detector, a quarter-balboa-detector, a doorstop, or a deadly frequent event, one might suppose.
weapon. In its new role there might be some brief period of confusion or Presumably, Fodor and company will not want to disagree with this indeterminacy. How long a track record must something accumulate before it treatment of artifacts, which have, they claim, no smidgen of real intention-is no longer a two-bitser but a quarter-balboa-detector (a "q-balber," we ality, but they may begin to worry that I have maneuvered them onto a might call it)? On its very debut as a q-balber, after ten years of faithful buttered slide, for now let's consider the exactly parallel case of what the service as a two-bitser, is the state it goes into when presented with a quarter-frog's eye tells the frog's brain. In Lettvin, Maturana, McCulloch, and Pitts'
balboa a
veridical
detection of a quarter-balboa, or might there be a sort of classic article (1959)—another Institute of Radio Engineers masterpiece—
force-of-habit error of nostalgia, a mistaken acceptance of a quarter-balboa
as
they showed that the frog's visual system is sensitive to small moving dark a U.S. quarter?
spots on the retina, tiny shadows cast in almost all natural circumstances by As described, the two-bitser is ludicrously too simple to count as having flies flying by in the vicinity. This "fly-detector" mechanism is appropriately the sort of memory we have of our past experiences, but we might take the wired to the hair trigger in the frog's tongue, which handily explains how first step in the direction of providing it with one. Suppose it has a counter on frogs feed themselves in a cruel world and thereby help propagate their kind.
it, which advances each time it goes into its acceptance state, and which Now, what
does
the frog's eye tell the frog's brain? That there is a fly out stands, after its ten years of service, at 1,435,792. Suppose the counter is not there, or that there is a fly-or-a-"slug" ( a fake fly of one sort or another ) or a reset to zero when it is moved to Panama, so that after its debut acceptance of thing of kind
F
(whatever kind of thing reliably triggers this visual gadget)?
a quarter-balboa, it reads 1,435,793. Does this tip the balance in favor of the Millikan, Israel, and I, as Darwinian meaning theorists, have all discussed claim that it has not yet switched to the task of identifying quarter-this very case, and Fodor pounces on it to show what is wrong, by 408 THE EVOLUTION OF MEANINGS
The Quest for Real Meaning
409
his lights, with any evolutionary account of such meanings: they are too another? This is the notorious Twin Earth thought experiment of Hilary indeterminate. They fail to distinguish, as they ought, between such frog-eye Putnam (1975). I am reluctant to go into the details, but I have learned that reports as "fly here now" and "fly or small dark projectile here now" and so nothing short of spelling it all out and blocking all the exits will have a prayer forth. But this is false. We can use the frog's environment of selection (to the of persuading those whose allegiances lie with original intentionality. So with extent that we can determine what it has been ) to distinguish between the apologies, here goes. Armed with our background briefing on the two-bitser various candidates. To do this, we use exactly the same considerations we and the frog, we can see exactly what the Twin Earth thought experiment used to settle the questions—to the extent that they were worth trying to depends on for its undeniable rhetorical force. Twin Earth, let's suppose, is a settle—about the meaning of the state in the two-bitser. And to the extent that planet almost exactly like Earth, except that there are no horses on Twin there is just no telling what that environment of selection has been, there is Earth. There are animals that look just like horses, and are called "horses" by also just no fact of the matter about what the frog-eye report
really
means.
the inhabitants of Twin Boston and Twin London,
"chev-aux"
by the This can be brought home vividly by sending the frog to Panama— or, more inhabitants of Twin Paris, and so forth—that's how similar Twin Earth is to precisely, sending the frog to a novel selective environment.
Earth. But these Twin Earth animals are not horses; they are something else.
Suppose scientists gather up a small population of frogs of some fly-Call them
schmorses,
and if you like, you may suppose they are a sort of grabbing species, on the brink of extinction, and put them under protective pseudo-mammal, a hairy reptile or whatever—this is philosophy, and you get custody in a new environment—a special frog zoo in which there are no flies to make up whatever details you find you need to make your thought at all but, rather, zookeepers who periodically arrange to launch little food experiment "work." Now comes the dramatic part. One night, while you pellets past the frogs in their care. To their delight, it works; the frogs thrive sleep, you are whisked off to Twin Earth. (It is important that you sleep by zapping their tongues for these pellets, and after a while there is a crowd through this momentous change, for that keeps you in the dark about what of descendant frogs who have never in their lives seen a fly, only pellets.
has happened to you—it keeps you "in the same state" you were in on Earth.) What do
their
eyes tell
their
brains? If you insist on saying the meaning When you awake, you look out the window and a schmorse gallops by. "Lo, hasn't changed, you are in a bind, for this is simply an artificially clear a horse!" you say (out loud or just to yourself, it makes no difference). To instance of what happens in natural selection all the time: exaptation. As make the case simple, let's suppose Twining, a handy Twin Earth-ling, utters Darwin was careful to remind us, the reuse of machinery for new purposes is the very same sounds at the very same time when he, too, sees the schmorse one of the secrets of Mother Nature's success. We can drive home the point, gallop by. Here is what Putnam and others insist on: Twining says, and to any who wish some further persuasion, by supposing that the captive frogs thinks, something
true
—namely, that a schmorse has just run by. You, do not all do equally well, because, due to variation in pellet detecting Earthling that you still are, say and think something/alse—namely, that a prowess in their eyes, some eat less heartily than others, and leave less horse has just run by. How long, though, would you have to live on Twin progeny as a result. In short order there will have been undeniable selection Earth, calling schmorses "horses" (just like all the natives), before the state of for pellet detection—though it would be a mistake to ask exactly when your
mind
(or what your eye tells your brain ) is a
truth about schmorses
enough of this has occurred for it to "count."