Quote Originally Posted by LucidFlanders View Post
If aliens existed with tech the way these guys talk about we would have seen them by now.
I always wonder about this frame of mind, when people use it to deny things like the possibility of metaphysics, alien life, ect. Exactly what is the factual basis of this statement? I mean, when else in history, has there been something so analogous to our finding out that there is an advanced civilization living among us - possibly with technology advanced enough as to blind our (cosmically limited) perceptions to their existence - that it warrants saying "well, if it were true, we would know it by now"?

How do you know this, exactly?