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Viruses of the Mind
Richard Dawkins
1991
The haven all memes depend on reaching is the human mind, but a
human mind is itself an artifact created when memes restructure a
human brain in order to make it a better habitat for memes. The
avenues for entry and departure are modified to suit local conditions,
and strengthened by various artificial devices that enhance fidelity
and prolixity of replication: native Chinese minds differ dramatically
from native French minds, and literate minds differ from illiterate
minds. What memes provide in return to the organisms in which
they reside is an incalculable store of advantages --- with some
Trojan horses thrown in for good measure. . .
Daniel Dennett, Consciousness Explained
1 Duplication Fodder
A beautiful child close to me, six and the apple of her father's eye, believes
that Thomas the Tank Engine really exists. She believes in Father
Christmas, and when she grows up her ambition is to be a tooth fairy. She
and her school-friends believe the solemn word of respected adults that
tooth fairies and Father Christmas really exist. This little girl is of an age to
believe whatever you tell her. If you tell her about witches changing princes
into frogs she will believe you. If you tell her that bad children roast forever
in hell she will have nightmares. I have just discovered that without her
father's consent this sweet, trusting, gullible six-year-old is being sent, for
weekly instruction, to a Roman Catholic nun. What chance has she?
A human child is shaped by evolution to soak up the culture of her people.
Most obviously, she learns the essentials of their language in a matter of
months. A large dictionary of words to speak, an encyclopedia of
information to speak about, complicated syntactic and semantic rules to
order the speaking, are all transferred from older brains into hers well
before she reaches half her adult size. When you are pre-programmed to
absorb useful information at a high rate, it is hard to shut out pernicious
or damaging information at the same time. With so many mindbytes to be
downloaded, so many mental codons to be replicated, it is no wonder that
child brains are gullible, open to almost any suggestion, vulnerable to
subversion, easy prey to Moonies, Scientologists and nuns. Like
immune-deficient patients, children are wide open to mental infections
that adults might brush off without effort.
DNA, too, includes parasitic code. Cellular machinery is extremely good at
copying DNA. Where DNA is concerned, it seems to have an eagerness to
copy, seems eager to be copied. The cell nucleus is a paradise for DNA,
humming with sophisticated, fast, and accurate duplicating machinery.
Cellular machinery is so friendly towards DNA duplication that it is small
wonder cells play host to DNA parasites --- viruses, viroids, plasmids and a
riff-raff of other genetic fellow travelers. Parasitic DNA even gets itself
spliced seamlessly into the chromosomes themselves. ``Jumping genes''
and stretches of ``selfish DNA'' cut or copy themselves out of chromosomes
and paste themselves in elsewhere. Deadly oncogenes are almost
impossible to distinguish from the legitimate genes between which they are
spliced. In evolutionary time, there is probably a continual traffic from
``straight'' genes to ``outlaw,'' and back again (Dawkins, 1982). DNA is just
DNA. The only thing that distinguishes viral DNA from host DNA is its
expected method of passing into future generations. ``Legitimate'' host
DNA is just DNA that aspires to pass into the next generation via the
orthodox route of sperm or egg. ``Outlaw'' or parasitic DNA is just DNA that
looks to a quicker, less cooperative route to the future, via a squeezed
droplet or a smear of blood, rather than via a sperm or egg.
For data on a floppy disc, a computer is a humming paradise just as cell
nuclei hum with eagerness to duplicate DNA. Computers and their
associated disc and tape readers are designed with high fidelity in mind.
As with DNA molecules, magnetized bytes don't literally ``want'' to be
faithfully copied. Nevertheless, you can write a computer program that
takes steps to duplicate itself. Not just duplicate itself within one computer
but spread itself to other computers. Computers are so good at copying
bytes, and so good at faithfully obeying the instructions contained in those
bytes, that they are sitting ducks to self-replicating programs: wide open to
subversion by software parasites. Any cynic familiar with the theory of
selfish genes and memes would have known that modern personal
computers, with their promiscuous traffic of floppy discs and e-mail links,
were just asking for trouble. The only surprising thing about the current
epidemic of computer viruses is that it has been so long in coming.
2 Computer Viruses: a Model for an
Informational Epidemiology
Computer viruses are pieces of code that graft themselves into existing,
legitimate programs and subvert the normal actions of those programs.
They may travel on exchanged floppy disks, or over networks. They are
technically distinguished from ``worms'' which are whole programs in their
own right, usually traveling over networks. Rather different are ``Trojan
horses,'' a third category of destructive programs, which are not in
themselves self-replicating but rely on humans to replicate them because
of their pornographic or otherwise appealing content. Both viruses and
worms are programs that actually say, in computer language, ``Duplicate
me.'' Both may do other things that make their presence felt and perhaps
satisfy the hole-in-corner vanity of their authors. These side-effects may be
``humorous'' (like the virus that makes the Macintosh's built-in
loudspeaker enunciate the words ``Don't panic,'' with predictably opposite
effect); malicious (like the numerous IBM viruses that erase the hard disk
after a sniggering screen-announcement of the impending disaster);
political (like the Spanish Telecom and Beijing viruses that protest about
telephone costs and massacred students respectively); or simply
inadvertent (the programmer is incompetent to handle the low-level
system calls required to write an effective virus or worm). The famous
Internet Worm, which paralyzed much of the computing power of the
United States on November 2, 1988, was not intended (very) maliciously
but got out of control and, within 24 hours, had clogged around 6,000
computer memories with exponentially multiplying copies of itself.
``Memes now spread around the world at the speed of light, and replicate
at rates that make even fruit flies and yeast cells look glacial in comparison.
They leap promiscuously from vehicle to vehicle, and from medium to
medium, and are proving to be virtually unquarantinable'' (Dennett 1990,
p.131). Viruses aren't limited to electronic media such as disks and data
lines. On its way from one computer to another, a virus may pass through
printing ink, light rays in a human lens, optic nerve impulses and finger
muscle contractions. A computer fanciers' magazine that printed the text
of a virus program for the interest of its readers has been widely
condemned. Indeed, such is the appeal of the virus idea to a certain kind of
puerile mentality (the masculine gender is used advisedly), that
publication of any kind of ``how to'' information on designing virus
programs is rightly seen as an irresponsible act.
I am not going to publish any virus code. But there are certain tricks of
effective virus design that are sufficiently well known, even obvious, that it
will do no harm to mention them, as I need to do to develop my theme.
They all stem from the virus's need to evade detection while it is spreading.
A virus that clones itself too prolifically within one computer will soon be
detected because the symptoms of clogging will become too obvious to
ignore. For this reason many virus programs check, before infecting a
system, to make sure that they are not already on that system. Incidentally,
this opens the way for a defense against viruses that is analogous to
immunization. In the days before a specific anti-virus program was
available, I myself responded to an early infection of my own hard disk by
means of a crude ``vaccination.'' Instead of deleting the virus that I had
detected, I simply disabled its coded instructions, leaving the ``shell'' of the
virus with its characteristic external ``signature'' intact. In theory,
subsequent members of the same virus species that arrived in my system
should have recognized the signature of their own kind and refrained from
trying to double-infect. I don't know whether this immunization really
worked, but in those days it probably was worth while ``gutting'' a virus
and leaving a shell like this, rather than simply removing it lock, stock and
barrel. Nowadays it is better to hand the problem over to one of the
professionally written anti-virus programs.
A virus that is too virulent will be rapidly detected and scotched. A virus
that instantly and catastrophically sabotages every computer in which it
finds itself will not find itself in many computers. It may have a most
amusing effect on one computer ---- erase an entire doctoral thesis or
something equally side-splitting --- but it won't spread as an epidemic.
Some viruses, therefore, are designed to have an effect that is small
enough to be difficult to detect, but which may nevertheless be extremely
damaging. There is one type, which, instead of erasing disk sectors
wholesale, attacks only spreadsheets, making a few random changes in
the (usually financial) quantities entered in the rows and columns. Other
viruses evade detection by being triggered probabilistically, for example
erasing only one in 16 of the hard disks infected. Yet other viruses employ
the time-bomb principle. Most modern computers are ``aware'' of the date,
and viruses have been triggered to manifest themselves all around the
world, on a particular date such as Friday 13th or April Fool's Day. From
the parasitic point of view, it doesn't matter how catastrophic the eventual
attack is, provided the virus has had plenty of opportunity to spread first (a
disturbing analogy to the Medawar/Williams theory of ageing: we are the
victims of lethal and sub-lethal genes that mature only after we have had
plenty of time to reproduce (Williams, 1957)). In defense, some large
companies go so far as to set aside one ``miner's canary'' among their fleet
of computers, and advance its internal calendar a week so that any
time-bomb viruses will reveal themselves prematurely before the big day.
Again predictably, the epidemic of computer viruses has triggered an arms
race. Anti-viral software is doing a roaring trade. These antidote programs
-- ``Interferon,'' ``Vaccine,'' ``Gatekeeper'' and others --- employ a diverse
armory of tricks. Some are written with specific, known and named viruses
in mind. Others intercept any attempt to meddle with sensitive system
areas of memory and warn the user.
The virus principle could, in theory, be used for non-malicious, even
beneficial purposes. Thimbleby (1991) coins the phrase ``liveware'' for his
already-implemented use of the infection principle for keeping multiple
copies of databases up to date. Every time a disk containing the database
is plugged into a computer, it looks to see whether there is already another
copy present on the local hard disk. If there is, each copy is updated in the
light of the other. So, with a bit of luck, it doesn't matter which member of
a circle of colleagues enters, say, a new bibliographical citation on his
personal disk. His newly entered information will readily infect the disks of
his colleagues (because the colleagues promiscuously insert their disks
into one another's computers) and will spread like an epidemic around the
circle. Thimbleby's liveware is not entirely virus-like: it could not spread to
just anybody's computer and do damage. It spreads data only to
already-existing copies of its own database; and you will not be infected by
liveware unless you positively opt for infection.
Incidentally, Thimbleby, who is much concerned with the virus menace,
points out that you can gain some protection by using computer systems
that other people don't use. The usual justification for purchasing today's
numerically dominant computer is simply and solely that it is numerically
dominant. Almost every knowledgeable person agrees that, in terms of
quality and especially user-friendliness, the rival, minority system is
superior. Nevertheless, ubiquity is held to be good in itself, sufficient to
outweigh sheer quality. Buy the same (albeit inferior) computer as your
colleagues, the argument goes, and you'll be able to benefit from shared
software, and from a generally large circulation of available software. The
irony is that, with the advent of the virus plague, ``benefit'' is not all that
you are likely to get. Not only should we all be very hesitant before we
accept a disk from a colleague. We should also be aware that, if we join a
large community of users of a particular make of computer, we are also
joining a large community of viruses --- even, it turns out,
disproportionately larger.
Returning to possible uses of viruses for positive purposes, there are
proposals to exploit the ``poacher turned gamekeeper'' principle, and ``set
a thief to catch a thief.'' A simple way would be to take any of the existing
anti-viral programs and load it, as a ``warhead,'' into a harmless
self-replicating virus. From a ``public health'' point of view, a spreading
epidemic of anti-viral software could be especially beneficial because the
computers most vulnerable to malicious viruses --- those whose owners
are promiscuous in the exchange of pirated programs --- will also be most
vulnerable to infection by the healing anti-virus. A more penetrating
anti-virus might --- as in the immune system --- ``learn'' or ``evolve'' an
improved capacity to attack whatever viruses it encountered.
I can imagine other uses of the computer virus principle which, if not
exactly altruistic, are at least constructive enough to escape the charge of
pure vandalism. A computer company might wish to do market research
on the habits of its customers, with a view to improving the design of
future products. Do users like to choose files by pictorial icon, or do they
opt to display them by textual name only? How deeply do people nest
folders (directories) within one another? Do people settle down for a long
session with only one program, say a word processors, or are they
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