In some situations such as a ritual, the entirety of a tribe may see spirits - but the modern Western anthropologist who is also present sees nothing. Are spirits really there?
Most Western people would say no; and they would explain-away the observing of spirits as some kind of group hypnosis, or wishful thinking, or a conjuring trick of the shaman... or something. Because modern people know (or rather assume as a metaphysical certainty) that spirits don't exist - therefore it doesn't matter what people say or claim: there were no spirits.
Yet, of course, everything we know about everything depends on no more than a consensus among people who report it; or perhaps a consensus among people in some restricted category - sensible people, intelligent people, adults, calm people...
Implicitly, therefore, the modern Westerners claim that all people who see spirits are unreliable, and over-emotional, gullible, unintelligent, immature, dishonest - or something of the kind. When whole tribes or societies claim see spirits - then this is exactly how modern Western people actually, in practice, regard them (although of course they are too afraid, or feel to guilty, actually to say so).
Yet there is something different about spirits... The Western anthropologist and the tribe he is studying all see most things in common - they see the huts, the spears, the food, the animals... but when it comes to spirits the tribe see them and the anthropologist doesn't.
There is something different about spirits - are the really there?
One thing than can be suggested is that there has been a change in human consciousness between the traditional Tribal Man and the modern Western Man. Tribal Man may regard stones as alive and plants as conscious... and he sees spirits.
All true - consciousness differs; but since we are not postmodern relativists - we can still ask what is really going-on. When Tribal Man sees a spirit - is there an object there, or not?
My understanding is that the seeing of spirits is an example of what Owen Barfield calls Original Participation. There is a spirit, but there is no object because it is immaterial - and the evolution of consciousness includes that Modern Man cannot perceive the immaterial...
Why is this? The given answer is that by Not seeing the immaterial, Modern Man is made free.
That which we perceive makes us passive - it is given, we are not free not to respond to it - because the mechanism by which we know it is unconscious. Tribal Man sees spirits, and spirits dominate him in the same way that Modern Man is dominated by whatever he sees.
Where Modern Man goes wrong is is asserting that because he cannot perceive spirits (and neither can he detect spirits with any technology), the spirits are not there: typically, Modern Man claims that the imperceptible does not exist.
The way ahead is to Final Participation; so, what would a Man in Final Participation experience in the situation described? Would he see spirits? No - but he would know the spirits were real. Instead of perceiving, he would know directly.
A Man in Final Participation would consciously know that spirits were present, would know about them (what kind of spirits and where) - but he would not see, hear, touch smell or taste spirits. What is the advantage in that? The answer is Freedom - the answer is Agency.
In Final Participation knowledge is in conscious thinking (i.e. 'primary thinking') - hence all knowledge is thinkable, all thoughts are inter-relatable.
All (primary) thinking (in FP) is real and true.
But the perceiving of Tribal Man is Not real and true - because perceptions are not complete; because all perceptions need to be interpreted. Tribal Man may see spirits, but he must still make sense of what he sees, and there is no guarantee that he will understand spirits correctly - indeed different people in the tribe will probably interpret what they have seen very differently.
Seeing is Not believing; because seeing is incomplete.
It is better Not to see, but instead to know directly - because what is known directly is true. That is why Final Participation is 'final' - because it is true; and it is also Final because it is divine. God knows by Final Participation - once FP is attained, there is nowhere further to go: it is indeed final.