The fact that people tend to think of any kind of "real evidence" as something scientific is quite ironic. The "taboos" of the scientific community were simply implemented to destroy as much countering opinions as possible, including religion. What is ironic about this is that SCIENCE IN ITSELF IS A RELIGION. Like all the faiths of the world, it is just another, more modern medium with which humanity attempts to describe the world. Just because science can be backed up by a series of mathematical equations doesn't mean it is more reliable than the whims of a deity.
Human beings are imperfect. So whoever is seeking for a "rational" explanation of the inexplicable (your ghosts, his phobia, their hallucinations) is really just wallowing in a sea of subjectivity. Even the word "rational" was conceived by a mind striving to describe.
We all know the limitations of language, even music (though it does seem to be the most accurate in conveying emotions). Such is the case with religion, to which science also belongs. Call it crazy, but no one in their right mind can rightfully give a brainchild of humanity the final word. Not religion. Not science. Because like its creators, it has its exceptions. And its faults. By believing in either one of these, we are not getting closer to the eradication of ignorance. We are simply creating FABRICATED REALITIES for ourselves. I warned you. Don't come running to me when Einstein's theory of relativity is crushed by yet another "breakthrough discovery." Seriously, people. Don't get ahead of yourselves. Stop weaving your own spider web wherein you will one day get caught in yourself.
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Now as for my opinion of the supernatural. To me, it is a figment of the human mind, as well as a display of our imagination. Like religion (and science, if you still want to separate it), ghosts and psychic phenomena are a showdown of our subconscious creating a sub-reality. Call it daydreaming, hallucinating, prophesizing- or refer to it as something tangible. (Honestly, the imagination and the tangible are really not that far removed. For example, it takes a simple motion of the lips to create the argument we had imagined would play out).
Such things are especially prominent with things that we fear. It takes a simple exaggeration of the mind to give an almost tangible substance to our bad dreams, guilt, or to the spirits of the dead. "I think, therefore I am." Our thoughts our more powerful than you'd think. If you imagine, you can also create.
I don't believe in ghosts. But I believe in energy and atmosphere. Our thoughts/ brains emanate an electric/thermal energy that could sometimes result as interpreted acts of telekinesis, for example. Me and my peers have busted a couple of light bulbs in the heat of an argument without ever touching them.
Nothing is rational, because the term in itself is subjective. However, though I cannot say that I believe in tangible ghosts or phenomena, there is an energy- specifically that of the brain- that is sometimes capable of creating realities larger than life. Maybe it's a protective measure, a means of expression that, if withheld, would be destructive to our thought processes. In any case, it is given power in moments of intense emotional trauma.