Ghosts: Physical Evidence (…not)

“…just because you can’t explain something doesn’t make it supernatural. It merely makes it unexplained – so far.”

Question from Edgar:
I’ve met people who claim to have experienced, or known someone who has experienced, physical encouters with “ghosts”. They claim to have been scratched and had witnesses who testified to them(the scratches). Also, some claimed that they shared paranormal experiences. By that I mean, multiple people seeing or hearing the same thing. How can two or more people hallucinate, or imagine the same exact thing?

I am 19 years old and have considered myself an atheist since 8th grade. When a theist finds out I am a non-believer, they feel they have to challenge me. I have no trouble providing overwhelming evidence(to them) regarding evolution vs creationism. However, I am always stumped when the subject of ghosts emerges. When I am at a loss for words, and they feel they have “defeated” me, they inform me(in their most condescending tone) that I am so naive. That I will one day learn the error of my ways. I need help.

If people feel they have to challenge you, imagine what they throw at a website called Ask the Atheist.

To address the specific claims above, just because someone has real scratches doesn’t mean a ghost made them (anything could have), and assuming you have several people claiming the shared experience instead of just one guy saying others had it too, if something looks or sounds like a ghost in the first impression when multiple people are present, they may well think it is a ghost and reinforce each other’s belief or credulity.

Speaking more generally, what you’re dealing with is either anecdotal evidence or at best circumstantial evidence. The stories of shared experiences are not accompanied by photos or recordings so that others might share in them, so stories or anecdotes are all they are. The scratches might have been made by a ghost, or they might be from scraping a wooden bookcase without noticing before or during the event. None of it proves anything, or goes any distance towards establishing any facts.

Even more broadly speaking, just because you can’t explain something doesn’t make it supernatural. It merely makes it unexplained – so far. Out of the possible explanations, even if they’re quirky or unintuitive, it’s worth asking out loud whether all the natural explanations combined are less likely than an actual ghost of which there is now no trace.

If you’re dealing with any famous claims, rather than friend-of-a-friend stuff, send them in as questions or comments to this question and I’ll see if I can help with some basic research.