Allan, I am of course aware of that (actually, it would probably take time, but even if the annihilation were instantaneous the argument would not be affected).
There are 4 possibilities:
The LHC would destroy Earth, but it fails to operate
The LHC destroys Earth
The LHC would not destroy Earth, but it fails anyway
The LHC works and does not destroy Earth
The fact that conditional on survival possibility 2 must not have happened has no effect on the relative probabilities of possibility 1 and possibility 3.
Allan, I am of course aware of that (actually, it would probably take time, but even if the annihilation were instantaneous the argument would not be affected).
There are 4 possibilities:
The LHC would destroy Earth, but it fails to operate
The LHC destroys Earth
The LHC would not destroy Earth, but it fails anyway
The LHC works and does not destroy Earth
The fact that conditional on survival possibility 2 must not have happened has no effect on the relative probabilities of possibility 1 and possibility 3.