I would suggest that science does not validate in any way the presence of spirits or ghosts. This doesn't mean that they don't exist of course, but they don't seem to be amenable to serious scientific inquiry. So, if one wants to believe in such things, no problem, but it will almost certainly be on the basis of personal experience or/and anecdotal accounts.
Yes, you do get some scientists who think that belief in the paranormal is justified scientifically, but the methodology of science doesn't seem to substantiate their findings. One such is Rupert Sheldrake, but the methodology he has employed in his experiments is extremely suspect and generally found wanting.