Re: @JeffyPoooh
"If I told you there was a massive hoard of ravenous 30-foot tall flesh-eating purple monsters outside your house and you looked out a window and saw that there were no such monsters, would you then be unable to prove I was lying via a negative result"
Let's make the analogy more accurate. Firstly, lots of people have been reporting to you that they have been seeing a purple monster. Though you didn't see one when you looked out of your window lots of your neighbours say that they have.
Secondly, instead of whether or not a 30-foot tall flesh eating purple monster exists, lets say that it's whether or not a new and large scale technology could have a side effect.
There, now your analogy is better and less loaded. Glad I could help.