Real adulthood is knowing there's no logical way to unconditionally prove those particular negatives. What you do with that information is another discussion.

Edit: Also if anybody is interested in reading up in an absolutely fascinating phenomenon, this was a topic that came up during my hospice / palliative care rotations. This article in particular is a systematic review from last year.

One of the most fascinating things about this phenomenon is that it's markedly different from the hallucinations seen with psychosis and delirium (which I'm more familiar with, my specialty being psychiatry). In particular the person experiencing it presents with orientation and cognition that is completely logical, linear, and otherwise intact.

A patient with psychosis often presents with poor understanding of their situation overall, such as not knowing where they are, not remembering recent events, or sometimes not even recognizing themselves. Their speech also usually presents with either thought blocking / poverty of thought, or the opposite—tangentiality / flight of ideas where their statements don't logically follow each other.

Meanwhile patients reporting death visions are typically able to accurately recall where they are, what has been happening, what is likely to happen next, and retain the ability to have linear and reality based discussions. They just also report seeing deceased family or pets, religious figures, etc.

Fascinating topic.