Darwin's Dangerous Idea (80 page)

"truth" by testing a candidate proposition against their existing data properties, mere
as if
semantical properties. What red and green were, really, bases.8

were very, very complicated
syntactical
properties. These philosophers Since the two systems were created independently, they cannot declined, however, to say anything further about just what syntactical plausibly be supposed to contain
exactly
the same truths (actually or properties these were, or to explain how even young children could swiftly even virtually ), but, for the prank to work as well as I claim it did in and reliably produce instances of them, or recognize them. The philosophers the story, we must suppose a very large overlap, so that it was highly were nevertheless convinced that there
had
to be a purely syntactic unlikely that a truth generated by A would not be recognized as such description of the regularity, since, after all, the causal systems in question by B. Two considerations, I claim, make this plausible: (a) Al and Bo were "just" computers, and computers are "just" syntactic engines, not may live in different countries and have different native languages, capable of any real semanticity.

but they
inhabit the same world,
and (b) although there are kazil-lions

"I suppose," retorted Al and Bo, "that, if you had found
us
inside our black of true propositions about that world (our world), the fact that both Al boxes, playing a trick on you by following the same scheme, you would then and Bo set out to create
useful
data bases—containing the information relent and agree that the operative causal property was genuine truth (or that is relevant to all but the most recherche of human purposes—

believed truth, in any event). Can you propose any good reason for drawing would guarantee a high degree of overlap between the two such a distinction?" This led some to declare that in a certain important sense independently created systems. Although Al might know that at noon Al and Bo
had
been in the boxes, since they were responsible for creating the on his twentieth birthday his left foot was closer to the North respective data bases, as models of their own beliefs. It led others to deny that there really were any semantical or mentalistic proper-8. Since these are just boxes of truths, no support is hereby given to the "language of thought" hypothesis (Fodor 1975). I supposed that the world knowledge was stored in a quasi-linguistic form just to make the storytelling easier (which is probably also the 7. Some have argued that my account of patterns in Dennett 1991b is
epiphenomenalistn
reason motivating most researchers in cognitive science, who adopt the language-of-about content. This is my reply.

thought hypothesis out of convenience!).

420 THE EVOLUTION OF MEANINGS

Blocking the Exits
421

Pole than to the South Pole, and Bo had not forgotten that his first will be just as visible to them as to us, but they will be clueless about ASCII.

French teacher was named Dupont, these would not be truths that To them, this gift from outer space will exhibit an utterly mysterious reg-either would be apt to put in his data base. But if you doubt that the ularity, totally beyond all analytic probes,
unless
they hit upon the idea that mere fact that they were both intent on creating an internationally each box contains a
description of a world,
and that the descriptions are
of
useful encyclopedia would ensure such a close correspondence be
the same world.
It is the fact that each box bears multifarious semantic tween their respective data bases, just add, as an inelegant detail, the relationships to the same things, though expressed in different "terminology"

convenient fact that they compared notes as to topics to be covered and differently axiomatized, that grounds the regularity.

during their years of hacking.

When I tried this thought experiment out on Danny Hillis, creator of the (2)Why not just have Al and Bob (a fellow American), or, for that matter, Connection Machine, he thought immediately of a cryptographic "solution"

why not simply have a duplicate of Al's system in box B? Because it to the puzzle, and then granted that my solution could be profitably viewed must be the essence (oops!) of my story that no simple, feasibly as a special case of his solution: "Al and Bo were using
the world
as a 'one-discoverable
syntactic
matching up could explain the regu-larity. That time pad!'"—an apt allusion to a standard technique of encryption. You can is why Bo's system is in Swedish Lisp—to conceal from prying eyes see the point by imagining a variation. You and your best friend are about to the underlying
semantic
commonalities between the data structures be captured by hostile forces, who may know English but not much about consulted during A's sentence-generation task and B's sentence-your world. You both know Morse code, and hit upon the following translation-and-truth-testing task. The idea was to create two systems impromptu encryption scheme: for a dash, speak a truth; for a dot, speak a that exhibited the fascinating regularity of external be-havior falsehood. Your captors are permitted to listen to you two speak: "Birds lay described but that were internally as different as possible, so that
only
eggs, and toads fly. Chicago is a city, and my feet are not made of tin, and the fact that their respective innards were systematic
representations
baseball is played in August," you say, answering "No" ( dash-dot; dash-dash-of
a
common world could explain the regularity.

dash) to whatever your friend has just asked. Even if your captors know (3) We might pause to ask whether or not two such systems could ever be Morse code, unless they can determine the truth and falsity of these senso inscrutable as to be invulnerable to reverse engineering. Cryp-tences, they cannot detect the properties that stand for dot and dash. This tography has moved into such rarefied and arcane regions that one variation could be added to our fable, for spice, as follows. Instead of ship-should think thrice at least before declaring either way. I have no idea ping the computer systems in the boxes to Mars, we put Al and Bo in the whether anybody can make a sound argument to the effect that there boxes and ship them to Mars. The Martians will be as puzzled by them, if are unbreakable encryption schemes or that there aren't. But, en-they play the Morse-code prank, as by the computers, unless they draw the cryption aside, hackers will appreciate that all the convenient com-conclusion (obvious to us, but we're not Martians) that these things in the ments and other signposts one places in the "source code" when boxes are to be semantically interpreted.

composing a program vanish when the source code is "compiled,"

The point of the fable is simple. There is no substitute for the intentional leaving behind an
almost
impossible-to-decipher tangle of machine stance; either you adopt it, and explain the pattern by finding the semantic-instructions. "Decompiling" is sometimes possible in practice (is it level facts, or you will forever be baffled by the regularity—the
causal
always possible in principle?), though of course it won't restore the regularity—that is manifestly there. The same moral, we have seen, can be comments but just render salient the structures in the higher-level drawn about interpreting the historical facts of evolutionary history. Even if language. My assumption that the scientists' efforts at decompiling the you can describe, in matchless microdetail, every causal fact in the history of program and deciphering the data bases came to naught could be every giraffe who has ever lived, unless you go up a level or two and ask strengthened by postulating encryption, if need be.

"Why?"—hunting for the
reasons
endorsed by Mother Nature—you will never be able to
explain
the manifest regularities, such as the fact that In the story as told, we can agree that it is bizarre that the scientists never giraffes have come to have long necks, for instance. That is Dewey's point in thought of checking to see if there was an ASCII translation of the bit the quotation given earlier in this chapter.

streams running through the wire. How could they be so dense? Fair enough: At this juncture, if you are like many philosophers, you are attracted by the send the whole gadget ( boxes A and B, and the connecting wire ) to "Mars,"

claim that this thought experiment "works" only because boxes A and B are and let the alien scientists there try to figure out the regularity. The fact that artifacts whose intentionality, such as it is, is entirely derived and artifactual.

all a's cause reds, all ß's cause greens, and random bit strings cause ambers The data structures in their memories get their reference (if they 422 THE EVOLUTION OF MEANINGS

Safe Passage to the Future
423

get any at all) from indirect reliance on the sense organs, life histories, and prospect around for the ideal location, as best you can foresee, for a fixed purposes of their creators, Al and Bo. The real source of the meaning or truth installation that will be well supplied with water, sunlight, and whatever else or semanticity in the artifacts lies in these human artificers. (That was the your capsule (and the supersystem itself) will need for the duration. The point of the suggestion that in a certain sense Al and Bo
were
in their main drawback to such an installation or "plant" is that it cannot be moved if respective boxes.) Now, I
might
have told the story differently: inside the harm comes its way—if, say, someone decides to build a freeway right boxes were two
robots,
Al and Bo, which had each spent a longish "lifetime"

where it is located. The alternative strategy is much more sophisticated and scurrying around in the world gathering facts before getting in their respec-expensive, but avoids this drawback: design a mobile facility to house your tive boxes. I chose a simpler route, to forestall all the questions about capsule, along with the requisite sensors and early-warning devices so that it whether box A or box B was "really thinking," but we may now reinstate the can move out of harm's way and seek out new sources of energy and repair issues thereby finessed, since it is finally time to dispose once and for all of materials as it needs them. In short, build a giant robot and install the capsule the hunch that
original
intentionality could not emerge in any artifactual (with you inside it) in it.

"mind" without the intervention of a (human?) artificer. Suppose that is so.

These two basic strategies are copied from nature: they correspond Suppose, in other words, that, whatever differences there might be between a roughly to the division between plants and animals. Since the latter, more simple box of truths like box A and the fanciest imaginable robot, since both sophisticated, strategy better fits our purposes, let's suppose that you decide would just be artifacts, neither could have real—or original—intentionality,
to
build a robot to house your capsule. You should try to design this robot so but only the derivative intentionality borrowed from its creator. Now you are that above all else it "chooses" actions designed to further your interests, of ready for another thought experiment, a
reductio ad absur-dum
of that course. Don't call these mere switching points in your robot's control system supposition.

"choice" points if you think that this would imply that the robot had free will or consciousness, for I don't mean to smuggle any such contraband into the thought experiment. My point is uncontroversial: the power of any computer 4. S

9

AFE PASSAGE TO THE FUTURE

program lies in its capacity to execute
branching
instructions, zigging one way or another depending on some test it executes on the data then available Suppose you decided, for whatever reasons, that you wanted to experience to it, and my point is just that, as you plan your robot's control system, you life in the twenty-fifth century, and suppose that the only known way of would be wise to try to structure it so that whenever branching opportunities keeping your body alive that long required it to be placed in a hibernation confront it, it will tend to branch down that path that has the highest device of sorts. Let's suppose it's a "cryogenic chamber" that cools your body probability of serving
your
interests. You are, after all, the
raison d'etre
of down to a few degrees above absolute zero. In this chamber your body would the whole gadget. The idea of designing hardware and software that are be able to rest, suspended in a super-coma, for as long as you liked. You specifically attuned to the interests of a particular human individual is not could arrange to climb into the chamber, and its surrounding support capsule, even science fiction any more, though the particular design problems facing be put to sleep, and then automatically be awakened and released in 2401.

your robot-builders would be profoundly difficult engineering challenges, This is a time-honored science-fiction theme, of course.

somewhat beyond the state of the art today. This mobile entity would need a Designing the capsule itself is not your only engineering problem, since

"vision" system to guide its locomotion, and other "sensory" systems as well, the capsule must be protected and supplied with the requisite energy (for in addition to the self-monitoring capacities to inform it of its needs.

refrigeration, etc.) for over four hundred years. You will not be able to count Since you will be comatose throughout, and thus cannot stay awake to guide and plan its strategies, you will have to design the robot supersystem on your children and grandchildren for this stewardship, of course, since they to generate its own plans in response to changing circumstances over the will be long dead before the year 2401, and you would be most unwise to centuries. It must "know" how to "seek out" and "recognize" and then exploit presume that your more distant descendants, if any, will take a lively interest energy sources, how to move to safer territory, how to "anticipate" and then in your well-being. So you must design a supersystem to protect your capsule avoid dangers. With so much to be done, and done fast, you had best rely and to provide the energy it needs for four hundred years.