Everything born of duality inherits the quality of dualism.  That is, all things of this world, and the ‘other world’, have a dual nature.  Thus, it can be stated that something which is seen can also be unseen, and that which is unseen can be seen.  That which is known can be unknown, and that which is unknown can be known.

If someone tells you that they have seen a spirit or ghost, is it really possible?  If they see a ghost but you do not, does the ghost really exist or not? The ghost may really exist in their mind but not in yours.  Similarly, someone can deliberately imagine a ghost exists, but really know it does not, but can still convince you that it does.  Now the ghost really exists in your mind but not in the mind of the other.  As you can see, whether the ghost exists or not depends only on whether or not the mind perceives it.

As stated earlier, all created things have a dual nature.  Thus, we can say that if someone sees a ghost but someone else does not, then it can be stated that a ghost can be seen and the ghost cannot be seen.  The evidence of the existence of the ghost is real in the mind of the one who perceives the ghost. This perception is a perception of the mind only, and the mind (which by its very nature has the quality of duality) can perceive correctly or incorrectly; that is, its perception may be true or false.  The nature of perception, whether true perception or false perception, can only be grasped by that which is distinct from the mind—and that is pure consciousness.

One whose consciousness is pure will not have a distorted perception and will be able to distinguish between what is real and what is unreal.

Ghosts are unreal.  This means they have no real existence.  Their existence depends only on whether or not the mind perceives them.  The mind that perceives a ghost is the mind that is caught up in false perception. This doesn’t mean that the ghost is unreal to those who perceive it.  Certainly the ghost is real for them, and remains real for them so long as they continue to perceive it.  This false perception is not the same thing as imagination.  It is not correct to say that they imagine a ghost exists (though some people may only imagine it).  There are people who really do see ghosts, but again, this perception is false.  For example, if someone sees a rope in the dark and mistakes the rope for a snake, they may say they have seen a snake and really believe it is so.  They are convinced that they have seen a snake and no one can convince them otherwise. But the same rope if seen in the light would not be perceived as a snake at all, but only as a rope.  Similarly, when one is ignorant of the knowledge of ATMAN (soul) one may believe in ghosts, but when one is enlightened with the knowledge of ATMAN one perceives correctly and knows for certain that ghosts do not exist, have never existed, and can never exist.

The mind is an incredible instrument whose workings are barely understood.  But even if we consider only the information (about the mind) currently available to us we can begin to understand how it can be stated that “the ghost exist, the ghost does not exist.”  For example, it is well known that certain drugs can alter one’s perception and cause the state known as hallucination, which basically means that we see something that exists but which really doesn’t exist.  A person who is hallucinating will actually see things that others do not see.  The person is not imagining what he or she sees—they actually see it, even though it does not actually exist except in their mind.  Clearly, it is possible for someone to hallucinate without the use of drugs.  This self-induced hallucination is a state of mind.  False perception and false knowledge propagate one another and produce more hallucination.  All are the product of ignorance.

When we say that ghosts are the product of ignorance we are not saying that all those who claim to have seen a ghost are ignorant.  They may very well be intelligent people, but they are certainly not enlightened.  A person can possess a great deal of intellectual acumen and still live in self-deception and self-delusion. 

Ghosts have no power except the power we give them.  Similarly, ego is just a paper tiger; it has no power except the power we give it.  Ego is really a ghost, and all ghosts are really the apparitions of ego only. Where there is no ego, there are no ghosts either.  But when the phantom of ego is validated in the mind, one will be haunted by one’s memories, images, and impressions and will suffer from many misconceptions.  These misconceptions will produce more misperceptions and false knowledge, and this vicious cycle will continue until it is interrupted by the dawn of enlightenment. 

The mind is enlightened with Wisdom.  To remove false perception, wisdom is absolutely necessary.  Everyone should fill the mind with the knowledge of the Soul to dispel once and for all the mythology of ghosts, goblins, and spirits.

Objection:

“How can you be so sure that ghosts do not exist? Just because you have never seen one it doesn’t mean that others have not seen them.”

Reply:

I am certain that ghosts do not exist just as I am certain that the Earth is round and not flat, even though I have never actually traveled all the way around it. With my little knowledge of science I realize that the earth could not be a flat disk but must be spherical in nature. Likewise, with my little knowledge of the Soul I realize that the existence of ghosts is not possible. Soul-knowledge (ATAMGYAAN) gives me the following insights:

• Soul is eternal and unchangeable.  Soul has never been born, nor has it ever died.
• The Spirit-self is never born and never dies but is manifested in the form of Prana (Life Force).  This (Spirit-self) is the PURUSH. 
• The living soul, JIVATMAN, is born when PURUSH (Spirit) is joined with PRAKRITI (Nature). 
• This Jiva (living being) is accompanied by ego, intellect, mind, senses and body. 
• The Jiva ‘dies’ when the body disintegrates (when the body’s integrated components: Fire, Water, Earth, Air, and Space are pulled apart by forces inherent in PRAKRIT) according to the law of Cause and Effect (KARMA).
• By the same law of Cause and Effect, the Jiva is born again.
• The Jiva continues to revolve in a seemingly endless cycle of birth, life, and death so long as it remains caught up in Cause and Effect.
• When the Jiva dies, the mind does not die, nor do the senses, intellect or ego. These elements accompany the Jiva through all its existences.
• When the Jiva is enlightened it gains control over all these elements and ceases to be bound by the law of Cause and Effect: which means that it is no longer compelled by the law of Cause and Effect to be reborn.  This only happens when the Jiva has purified the ‘inner organ’ (Antarkarana comprised of ego, intellect, mind, and senses) to the point that the physical body (the ‘outer organ’) is no longer automatically (by the force of Nature) manifested or born.
• If the Jiva is not enlightened, it is automatically reborn at the time of death by the force of Nature.  The unenlightened Jiva has no choice in this matter. 
• The Jiva is never trapped in between the state of death and life, because no such state exists.  Either the Jiva is enlightened or not.  Either you are embodied or not.
• The spirit of the Jiva is the pranic energy of which the Jiva is the embodiment.  In other words, the Jiva is the manifestation of the Spirit Self joined with Nature and there is no separate ‘spirit’ from this. 
• The Jiva is the embodiment of Consciousness in the unconscious matter. The Spirit Self, in the form of the Jiva, cannot exist in a disembodied state except in the state of Liberation (Moksha or Enlightenment).  In other words, there is no such thing as a ‘spirit’ (which generally refers to a ‘being’ possessed of and by ego, intellect, mind and senses,  through which it functions but is supposedly able to do so without a physical body. This is simply not so, because such powers are accessible only to the enlightened.)
• The Jiva is the manifestation of the Spirit Self, and this manifestation (Jiva) remains bound by birth, life, and death until the time of liberation. According to the law of Cause and Effect the Jiva must be reborn unless it has attained the state of Enlightenment.
• Death is an effect of the cause of life. (In other words, death is a natural consequence of living.) Life (the life we are living now) is an effect of the cause of a previous life.  Death is the transition from one life to another life—it is not the cause of another life (for example, death by trauma cannot cause a person to become a so-called ghost or spirit trapped between life and death).  The way we live our life will cause us to live another life too, or it (our living) will ultimately lead to the deathless state, known as Liberation, or MOKSHA.
• Death comes naturally, according to the Law of Karma (the law of Cause and Effect), and rebirth also comes naturally, according to the same law.
• There is no law (or principle of existence) that says a soul can be trapped in a state in between death and rebirth. Only those who have no understanding of the Law of Reincarnation (as it relates to the Law of Karma) will believe that a being can become a ghost. A ghost is a phantom, and a phantom is a figment of the mind only.
• The reason a being cannot become a ghost is because it would violate the laws of Nature (the laws of Prakriti and Purush, the workings of Matter and Non-matter).  According to the laws of Nature, an unenlightened soul must be reborn to continue to reap the results of its actions.  The only time we are not reaping the results of our actions is in the state of deep dreamless sleep, or during the state of Samadhi, or during the state of Moksha (Liberation).  
• We pay for our Karma (words, thoughts, and deeds), that is, we reap the rewards of our actions, while awake and while dreaming.  Someone once said that “sleep (ordinary dream-sleep) is a short death, and death is a long sleep.”  If we believe that Death is like a dream-sleep state of mind, then we may also believe the soul stays in dream-sleep state of mind for a period of time before it is reborn.  But this dream-sleep state of mind has nothing to do with ghosts, goblins, and spirits. The things that happen in a dream are dream-like only; they are not ghost-like.  In other words, just as the characters in a dream have absolutely no control over, or interaction with, people, places, or things that are not part of the dream, in the same way, even if the soul remains in a dream-sleep state of mind for a period of time after death, it would not be possible for the soul to have any contact whatsoever with persons who are living, and no one who is living could have any contact with the person or persons that exist in the dream.
• Some people who have studied the Occult will say that a spirit or ghost is the astral body (subtle body) and that the astral body moves about in the astral world and sometimes interacts with persons possessing physical bodies.  This too is just a fairy tale, because the truth is that only a free soul (one who is enlightened) is able to move about in the Akashic dimension or plane, and such a one would only very rarely (if at all) appear in an astral form before the eyes of mortal beings, even before the eyes of very highly evolved mortal beings.  Ordinary people may of course have so-called out of body experiences, but these experiences have nothing to do with ghosts or spirits.  They are simply glimpses into a different dimension of our being (the non-physical dimension) and may occur naturally as a result of spiritual development, or unnaturally as a result of trauma or drug use.  In any case, all of these experiences have absolutely nothing to do with ghosts or spirits.
• Some persons postulate that all experiences are recorded in the Akash, and they say that these Akashic records can be read or viewed much like an audio or video recording.  They further postulate that it is possible to stumble upon these recordings without realizing that what is being experienced is a recording only, of some past (or even future) event.  In this way they explain how someone might see the figure of, for example, a person who lived a thousand years ago during the European Dark Ages.  The Akashic record, being an exact representation of the event, will display everything about the event exactly as it was at the time it was recorded, right down to the fine details of the clothing, hair-style, language, ornaments, etc.  Seeing such a thing, the person who experiences it feels that they have seen a ghost, when all they really experienced was an Akashic record.  This would explain how some persons think they have seen, for example, a departed loved one exactly as they looked when they were alive.  For instance, someone may see a little girl who died long ago. Obviously (that is, obviously if one has any knowledge of the nature of the Soul), the soul (Jivatma) can never get stuck in an image but is always evolving.  We never remain the same even for a second, but are constantly changing.  Thus, a soul who was living in the body of a little girl, and who met with an untimely death, will naturally move onto a different life, in a different body, and (very likely) in a different place.  If someone claims to see the same girl twenty years later, or a 100 years later, and tells us that the girl is just as she was previously, then that person has little or no understanding of the true nature of that little girl who died—they have no realization that the essence of the little girl is NOT a little girl, or young girl, or young woman, or middle aged woman, or old woman, or even a woman at all!  The soul left the body and moved on, and has already been reborn in another form, in another time, in another place.
• When we realize the purpose of our existence and know without any doubt that we are the children of GOD, we know for certain that the Divine Presence is always present, has always been present, and will always be present.  Living in that Presence, or even just being conscious of that Presence, opens our eyes to the Truth.  The truth is: what is Real is always Real, and what is unreal can never be Real.

In conclusion, everyone should banish from their mind any belief in the existence of ghosts, goblins, and spirits. It is a total waste of time and psychic energy to create in the mind any belief in that which is unreal.