Take money for example. It's certainly a potent force in the modern world. The financial system decides who lives where, who has what, and who has power over whom.
But what is it exactly, the universal force of money that holds humanity in its palm? Its only physical existence is in pieces of paper, books of accounts, and records in computer storage.
Money only has any authority at all because we allow it to. Outside our heads, it's impotent and useless. It's a fantasy, that exists only because we choose to believe it's real.
How about countries? The United States of America certainly seems to be a powerful force in the world. Its military straddles the globe and its culture touches us all. It provides its citizens with a strong sense of belonging and all sorts of other benefits.
But what is it exactly? Is it the White House and other government buildings? Is it the land upon which it rests? Is it the documents of its laws and history?
The United States of America is an idea that exists only in our heads.
And it's not even a very sharply defined idea. Virtually everyone has a view on what the US is and what it stands for, but these ideas are often very different. Listen to political opinions and you'll soon see that even its own citizens can't agree on what the USA is.
If everyone in the world chose not to believe in the Sun tomorrow, it would still continue to shine. If everyone chose not to believe in the USA , it would simply cease to exist. The land within its borders would still be there, like it has been for millions of years and will likely continue to be for millions more. The tanks, planes, and missiles would still exist. So would the movies, law books, music, and buildings. But the country itself would cease to be.
Like any country, it's only real because enough people choose to believe in it.
Once you get hold of this idea, you begin to see how much of what we identify as real is actually only human-created fantasy. The abstract concepts of justice, possession, and morality, for example, only have potency inside our minds. In the natural world they are nothing but ghosts.
This idea should not be confused with the many abstract concepts that have a bridge to the physical world. Mathematics is real, and can be proven to be so with real world examples. A plan of a bridge can find existence when that bridge is eventually built.
But how do you create morality in a form that can exist independently of our minds?
Of course, our belief in many of these ideas helps to build a better world. The illusion of money helps us to trade and build wealth. The mirage of justice allows us to see what's expected of us. The dream of nationality helps us feel that we belong to something bigger and more important than ourselves.
But sometimes, these castles in the sky can be very damaging.
The ideas of a dominant Nazi Germany and an imperial Japan caused the deaths of tens of millions during the Second World War. Yet those ideas vanished from existence within a decade of the war's end. This occurred not only because Germany and Japan were defeated, but also because the populations of those countries ceased to believe in their nationalist fantasies. What plunged the world into darkness for many years, simply vanished into thin air.
A similar pattern occurred with the fall of the USSR. Without a shot being fired, a superpower collapsed simply because its citizens stopped believing in it.
The problems that can grow because of what's inside our heads are presently apparent in the Middle East. The Israeli and Palestinian populations have powerful ideas about who they are and what they represent that are bitterly incompatible. They believe these ideas so strongly, that they are willing to die and kill to defend them.
History and current events show that the fantasies of humans can be very dangerous.
We also have a lot of difficulty pinning these beliefs down. If you and I have a disagreement about who's taller, we can simply stand side-by-side to resolve it. But how do we resolve our arguments about how a murderer should be punished? There's no objective way of measuring what's right when the physical world seems to have no understanding of justice.
To get around this problem, we attach enormous emotional significance to our fantasies. It may have no physical form, but surely if an idea can cause a strong emotional response within us and others it must be real? My opinion is more solid than yours, simply because I feel it more strongly. Or so we like to tell ourselves.
We use our emotions to compensate for the fact that what we believe is simply a mirage.
We should, from time to time, examine our beliefs no matter how emotionally attached to them we are - and ask one simple question. Does the evidence suggest that they improve the lives of ourselves and those around us?
If the answer is "no", then we should have the strength to let our rational mind overcome the emotional hold these beliefs have on us. And we should have the courage to change the way we think.