Yes, as psychological phenomena -- that is, I believe that people actually do see ghosts, sometimes. The shortcuts our brains take to make sense out of the flo

Yes, as psychological phenomena -- that is, I believe that people actually do see ghosts, sometimes. The shortcuts our brains take to make sense out of the flood of input from our senses mean that it's quite common to legitimately see things that aren't there, though. So I certainly don't believe there's anything actually there -- no troubled spirits, no influence from beyond the grave, any of that nonsense. If someday there's any supernatural phenomenon that stands up to a James Randi style test, I'll wonder what's going on. As it is, every "ghost story" I've ever encountered is far more easily explained by brain tricks and human error than anything remotely supernatural. "Absence of proof isn't proof of absence", but that also applies to teapots orbiting the Sun between Earth and Mars, of course... there's no sense in spending time chasing down silly ideas that aren't even rationally coherent when you dig into details.