Professor Frank Close of the University
of Oxford has been quoted as saying
that "The idea that it could cause the end of the world is
ridiculous." (http://www.telegraph.co.uk/news/2008/04/06/wcern106.xml). Is
it ridiculous because it is impossible, or because it is very unlikely? I don’t
think he knows it is impossible, and being very unlikely is not sufficient to
dismiss the risk. Yes, it’s very unlikely, but being very unlikely is not remotely
unlikely enough, as, I think, these three arguments demonstrate.

####
1^{st} Argument.

1.
A necessary condition on doing anything which might destroy
all present and future goodness is that the expected value of doing it is
positive

2.
Setting

*g*to be the total goodness (all present and future goodness) in the absence of running the LHC,*x*the factor by which running the LHC for a week increases goodness if it doesn’t bring total destruction, and*p*the chance of total destruction per week of running, then (*gx*–*g*) is the benefit that might be gained from a week’s running and the expected value is (1-*p*)(*gx*–*g*)-*pg*.
3.
For the expected value of one week’s running of LHC to
be positive we require (1-

*p*)(*gx*–*g*)-*pg*>0 i.e.*x*> 1/(1-*p*).
4.
Suppose

*p*is one billionth, then*x*> 1.000000001….
5.
So one week’s running of the LHC must increase total
goodness by more than one billionth for the expected value to be positive.

6.
But one week’s running of the LHC won’t increase total
goodness by anything like one billionth.

7.
Therefore the LHC should not be turned on.

####
2^{nd} Argument

8.
Suppose that a sufficient condition for it to be
permissible to do something which might bring on the destruction of all present
and future goodness is that the expected value of doing it is positive

9.
Let

*g*be the total goodness without doing that thing,*x*the factor by which doing it increases goodness if it doesn’t bring total destruction, and*p*the chance of total destruction. Then for the expected value to be positive requires*x*> 1/(1-*p*)
10. In
that case it would be permissible to risk total goodness by doing something
that risked total destruction with a chance of 50% provided it offered to
increase total goodness by more than twice.

11. But
not even doubling goodness justifies the risk of destroying all goodness.

12. Therefore
positive expected value is not sufficient to risk the destruction of all
present and future goodness.

####
3^{rd} Argument

13. Avoidable
risks of destruction of all present and future goodness should not be taken.

14. Turning
on LHC is an avoidable risk of destruction of all present and future goodness.

15. Therefore
it should not be turned on.

originally at http://www.practicalethics.ox.ac.uk/blog

originally at http://www.practicalethics.ox.ac.uk/blog

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