There is another kind of fraud possible:
> I have a box.
> I put your best friend in the box and a red light comes on.
> I say this means your best friend is guilty.
> Your friend is put to death.
> You have my word that the box and light does what I say it does.
> When I put myself in the box, the red light never comes on.
> Hmm, Joe Stalin had one of those.
There are two separate problems here. One is to verify that the
machine functions as it is supposed to. The thought experiment
assumes that this is possible. Another problem is to make sure that
the criminal code, compliance with which the subject is tested for,
is a good criminal code. (As long as there is free entry and exit
from a society, then libertarians would presumably not have anything
against a "Stalin-spaceship" (using Hal's spaceship terminology),
where people could sign in who wanted to live under a Stalinisque
dictature with perfect mind-scanning techniques. This does not mean,
of course, that the Stalin-spaceship would be a "good" society, one
where the libertarians would want to live.)
> Another problem: someone commits a heinous crime, then doses eirself with
> (say) a Rohypnol-Scopolamine cocktail that scrambles long term memory
> fixation. Chemically-induced amnesia. What does a brain scan reveal?
Realistically, mind-scans will probably not be possible until we are
digital, and then it would be even easier to forget at will. So one
could only scan for evil intentions, not for memories of commited
One can imagine a sci-fi plot as follows. A wants to become The
Leader, but every candidate for the leader role will have to undergo
repeated psycho-scans. So A splits into B and C. B is designed to run
for the presidency with pure methods and a good intentions. C on
the other hand will break into the opposition canditate office and
plant false evidence of some scandalous event. In the end, B becomes
president, and, having only socially accepted intentions, hunts C
down and puts him in prison.
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