Doubt.
There's probably no finer characteristic of humans (and maybe some other higher mammals) than doubt. I'm convinced that it is a large part of what made us successful as a species, at least thus far.
I can imagine prehistoric man developing into agrarian man due to his doubt in the naturally occurring food sources to continue to fall to his spear or drop into his hands. Doubt in the luck of natural and necessary resources to appear as required likely encouraged early humanoids to take matters into their own hands, planting food, breeding meat.
I can imagine builders of early empires doubting that those 'others' outside the domains of their rule might willingly coexist peacefully thus creating a necessity for expansion to ensure cooperation.
I can imagine that doubt has, in part won wars, fueled human inventiveness, stabilized societies suffering rapid expansion or contraction.
Usually we are quick to doubt. "HEY YOU WON A MILLIUN DOLLAHS!" on that envelope which naturally obscures the fine print detailing some hideous investment in unwanted literature which is usually the precondition for a miniscule chance that the previous statement is true. And adults often teach children the meaning of 'good reason to doubt' - as so romantically put "Yes, Virginia, there is a Santa Clause". Eventually doubt takes everyone. And that is good. But what puzzles me is why people are willing to suspend their natural instincts and clutch desperately to statements that under ordinary circumstances would generate the same looks of skepticism as the 'MILLIUN DOLLAHS' envelope.
It's not just religion I'm referring to, although that alone requires such a suspension of natural instinct that regular indoctrination is mandated to maintain belief. I'm not referring to our 'News' services (hello? they're run by PEOPLE - people who are paid and managed by larger organizations... all of whom HAVE a larger motivation in spending time and effort to feed you their version of events). I am speaking to the counter-doubting instincts in general of humans to want to believe what they are told when it suits their needs and re-enforces their mental security. It's religion. It's politics. It's a sense of belonging that runs so deep that any fracture leads to a fear of being ostracized that shakes most people to the core.
When people look back at WWII and wonder how the ordinary German could buy into the thought that Jews were less than human you understand what I'm saying.
I now what generations hence will think of our current crises, and wonder openly on where our doubts were, and how gullable we became in the second millennia.
If you have a doubt cherish it. It may mean you're actually thinking for yourself.