Do You Believe in Ghosts?

[Overbeing]

I am in no way superstitious, so I don't believe in anything paranormal or anything that can't be tested(proven) to a reasonable degree. I feel that if ghosts exist and could affect our world, it would be quantifiable and we would have some proof of that. To my knowledge, this has never happened, so if ghosts exist, they may as well not.
I'm curious why you believe that ghosts exist. Is it more that you like the thought/it is comforting to believe? What happened to make you think it is more likely that they are among us than any alternative?