How do I know I exist?
Existential issue
IN A nutshell, you don’t.
Philosopher René Descartes hit
the nail on the head when he wrote
“cogito ergo sum”. The only evidence
you have that you exist as a self-aware
being is your conscious experience
of thinking about your existence.
Beyond that you’re on your own. You
cannot access anyone else’s conscious
thoughts, so you will never know if
they are self-aware.
That was in 1644 and little progress
has been made since. If anything, we
are even less sure about the reality of
our own existence.
It is not so long ago that computers
became powerful enough to let us
create alternative worlds. We have
countless games and simulations
that are, effectively, worlds within our
world. As technology improves, these
simulated worlds will become ever more
sophisticated. The “original” universe
will eventually be populated by a nearinfinite number of advanced, virtual
civilisations. It is hard to imagine that
they will not contain autonomous,
conscious beings. Beings like you and me.
According to Nick Bostrom, a
philosopher at the University of Oxford
who first made this argument, this
simple fact makes it entirely plausible
that our reality is in fact a simulation
run by entities from a more advanced
civilisation.
How would we know? Bostrom
points out that the only way we could
be sure is if a message popped up
in front of our eyes saying: “You are
living in a computer simulation.” Or,
he says, if the operators transported
you to their reality (which, of course,
may itself be a simulation).
Although we are unlikely to get
proof, we might find some hints about
our reality. “I think it might be feasible
to get evidence that would at least give
weak clues,” says Bostrom.
Economist Robin Hanson of George
Mason University in Fairfax, Virginia,
is not so sure. If we did find anything
out, the operators could just rewind
everything back to a point where the
clue could be erased. “We won’t ever
notice if they don’t want us to,” Hanson
says. Anyway, seeking the truth might
even be asking for trouble. We could
be accused of ruining our creators’
fun and cause them to pull the plug.
Zombie invasion
Hanson has a slightly different take
on the argument. “Small simulations
should be far more numerous than
large ones,” he says. That’s why he
thinks it is far more likely that he lives
in a simulation where he is the only
conscious, interesting being. In other
words, everyone else is an extra: a
zombie, if you will. However, he would
have no way of knowing, which brings
us back to Descartes.
Of course, we do have access to a
technology that would have looked like
sorcery in Descartes’s day: the ability to
peer inside someone’s head and read
their thoughts. Unfortunately, that
doesn’t take us any nearer to knowing
whether they are sentient. “Even if you
measure brainwaves, you can never
know exactly what experience they
represent,” says psychologist Bruce
Hood at the University of Bristol, UK.
If anything, brain scanning has
undermined Descartes’s maxim. You,
too, might be a zombie. “I happen to be
one myself,” says Stanford University
philosopher Paul Skokowski. “And so,
even if you don’t realise it, are you.”
Skokowski’s assertion is based on
the belief, particularly common among
neuroscientists who study brain scans,
that we do not have free will. There is
no ghost in the machine; our actions
are driven by brain states that lie
entirely beyond our control. “I think,
therefore I am” might be an illusion.
So, it may well be that you live
in a computer simulation in which
you are the only self-aware creature.
I could well be a zombie and so
could you. Have an interesting day.

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