Wouldn't any evidence produced be labelled anecdotal by the Scientific community?, since its standard would be consistent verification, that any phenomena must be readily repeatable. But like Science, anecdotal evidence could be submitted as a pointer, as to what is implied by its effects. Science theorized Black Holes by observable effects, no? In the case for idealism it could be ghosts, spirits, demons and angels. In the case of ghosts it would point to consciousness without a body, thereby proving that it may not be a product of matter, where consciousness arises with matter and dies with matter. There have been enough cases of ghosts existing that it could at least establish a possibility. To sweep away all possibility as being impossible because it may have happened to "one" person seems ludicrous because if the same standard is applied to a scientist then no theory should ever be considered. Those who have had "other-worldy" experiences cannot be convinced that it was a product of their imagination or brain chemistry; they know what they experienced. To put their experiences into question begs the question as to why Science doesn't use the same standard to their theories? To say that it is impossible because everyone hasn't had that experience is to say that no one should be able to fly through the air like Michael Jordan or float through the air like Nijinsky.
Fascinating Secrets – Vaslav and Bronislava Nijinsky! - ILIL ARBEL
And yes, I have a few ghost stories of my own. No one can convince me that they were not real. I shant bother the community with details as the expectant result is very likely to be ridicule, so why bother?
The best retort may be that while ghosts may exist they are an obvious product of consciousness-within-a-body and therefore it doesn't prove that consciousness existed before the body. The "idealist" would then counter with angels and demons...
You cannot test it as an hypothesis. Any such experience would solely be yours and cannot be proven to another. For example, the children of Fatima saw other-worldly apparitions but no one else could see them.
FATIMA - The Children
To pique your imagination, or your scientific prejudices, "the Miracle of the Sun" at Fatima was described as
and "the sun" appeared as an opaque, spinning disc in the sky. It was said to be significantly duller than normal, and to cast multicolored lights across the landscape, the people, and the surrounding clouds. The sun was then reported to have careened towards the earth in a zigzag pattern." Sounds a lot like a UFO doesn't it?
Miracle of the Sun - Wikipedia, the free encyclopedia (Other descriptions are given in the article.) 40,000 to 100,000 people witnessed the evident. Is that enough proof that UFOs are real? It cannot be mass hypnosis or mass hysteria since others saw "it" from miles away.