This may be true if ones philosophy is science. Science exists to explain, and what it can't explain, there are some -- well, many, bad students of science who will swear to High Heaven that what they can't explain can not exist.
In Shakespeare's day, people thought ghosts were real, as real as a favorite uncle, who instead of going off to China somewhere and never returning or writing, passed over on the other side, and was a better relative than one who went off to China, because he returned and kept returning. Well, really he never left. There are a few -- well some, people who think that ghosts are with us, or with them, today.
A family from Coventry, England, have supposedly filmed what they claim is a ghost haunting their home. See the video.
Many -- well, most, people who watch this video will dismiss it as a dumb fake, and say that they have seen better tricks on TV. I don't know if what's happening in this video is legit. I don't know whether the door opened by itself and the chair was moved by an unseen, supernatural force.
I try to keep an open mind about everything, and have had some unexplained personal experiences with cold rooms and have sensed the presences of a person or two who have checked out of life. Yes, I'm being legit.
I haven't had a ghost in my house to my knowledge. I don't think I would complain if one came in now and then, and moved the sofa, so I could sweep and vacuum behind it. I could use some help sliding the heavy appliances. I haven't swept behind the refrigerator in years.