Why are people so stupid?Such a deeply, deeply philosophical question. And yet so frequently asked as to be nearly universal.
There are a multitude of reasons why people are so stupid, which partly explains stupidity's enduring popularity as an abundant element of the universe. So we'll list 'em, scientifically, and in no particular order.
Reason #1: Stupidity works.
You may or may not have noticed this, but humans are a rapidly growing element of earth's ecosystem. Since humanity's hardscrabble beginnings many thousands of years ago, all the way to the sophisticated complexity of today's sprawling mass of Other People, the human population on earth has been growing. Not consistently, not steadily, but relentlessly nonetheless. As species go, we are currently jaw-droppingly successful. In other words, there are more and more of us all the fucking time.
Stupidity has not hurt us one bit. We were stupid a long time ago, we are still stupid, and yet we continue to reproduce enormously successfully. Whether or not you are pleased with this turn of events I leave to you, but the underlying moral is clear:
Stupidity does not hamper reproduction! Stupid people breed. Stupidity may in fact help our ability to reproduce quite a bit. Anyone who has ever gotten married, had children and later wondered - why did I do that anyway? Oh yeah, that's right, I was really stupid - can attest to the helpful effects of stupidity on the mating, dating, and attraction process. Not thinking clearly is very helpful in making the whole mystery of chemical attraction seem worth pursuing.
On the other hand, thinking too clearly and being too smart or too sensible can really really fuck it up. Thinking too much can badly inhibit the bonding process. The bonding process, which is essential for human survival, doesn't give a damn about what we think of as smartness, it cares about irrationality and chemicals, both of which it highly values. None of us would put up with each other for a moment if it weren't for the saving graces of stupidity and bonding.
People occasionally and naturally get very confused about this, because they are taught to think that what makes us successful as a species is our intelligence. We think we rule the earth because we are smart. We do not rule the earth, and evolution does not select for smartness, it selects for survival. Cockroaches rule the earth and they are smart enough not to think it's because they have big brains.
This is not to say we aren't intelligent as a species, in fact, we are. But we are intelligent for a reason. Or actually a couple. One reason is that we are designed to be modular, adaptable to a wide variety of climates and environmental conditions from Alaska to the Congo. But so are a lot of other species, and they don't run around inventing indoor plumbing.
The other reason is that we have to get along with each other to survive. Again, we are not the only species like this - bees have to get along with each other too. But you combine our modularity with our need to get along and you get culture. Or a system in which individuals of the species can be born into any of a huge variety of cultures, none of which the organism can predict before its born, and the poor organism has to develop a big brain of a certain kind just to figure out what the fuck is going on and how it has to act to survive in its particular environment. Combine this with two other factors - language, which was probably an evolutionary accident (whoah, get a load of this!) and which creates many complications, and lack of bodily defenses like fur and claws - you've got something more or less resembling a human being.
It's this desperate need to get along with each other under unpredictable circumstances that makes us invent indoor plumbing and freeway systems and astrophysics. We have to fucking cooperate with each other to survive the elements and each other and so we turn a large portion of our efforts toward smartness. We don't have fur and we get cold peeing outside, so we invent plumbing. We don't have claws, so we invent arrows and guns. We need to keep in contact with each other so we invent freeways, so we can zip around meeting each other in various places. We might need astrophysics to keep asteroids from zooming into us. We have to figure out how the fuck to get along with each other, so we invent laws, and philosophy, and literature, and justice, and commerce and a whole bunch of other stuff. We do all this smart shit to survive, not because God loves smart shit. Roses don't act all that smart, but there's nothing to indicate God doesn't love them. We're smart because it's complicated being modular and social and defenseless and chatty. You need a big brain just to deal with all the fucking possibilities. Which is exactly what our brains are designed to do. Being smart doesn't make us human - being human made us smart.
All this emphasis on smartness might seem out of place in a rant on stupidity - but I bring it up for two reasons. One is the surprise factor. It's the fact that we're smart that makes us so wide-eyed with astonishment and anger when we realize how stupid we are - we expect better from ourselves - but that's only because we're stupid.
Our chatty defenseless modular sociability forced us to develop social brains to keep track of all the madness, and it is the social brain that thinks we're really smart. It values intelligence for its ability to come up with polio vaccines and electric lighting. Ironically, however, your social brain, the one that is patting you on the back for being smarter than everyone else - is also the part of your brain specifically designed to be incredibly fucking stupid. The other parts of your brain can't ignore reality, because they rely on it, sensory input, information about blood flow and volume and pressure and digestive juices, and hunger and fatigue and cold, and so on. Your social brain on the other hand, relies on Other People instead of reality, which inclines your Social Brain to dramatic outbursts of complete fucking idiocy.
Let's take an example. Wearing ties might be pretty fucking stupid, but a number of people have worn them over the years. Tying a knot around your neck might not seem like the best way to convince God that you're a smart species, but it's not by far the stupidest fashion idea any culture has ever come up with. There's always been heavy competition in that category (hey, how about we all stick a bone through our nose!). But the Social Brain, the one that encouraged us to build the automobile, will seize upon something like a tie, as if it was just as good an idea as Advil (which it wasn't by the way, Advil is one of the best ideas anybody has ever come up with, period).
Because the Social Brain reasons like this, 'I don't know why everybody around you is wearing ties to work, but if you want to survive this mess of a culture you got yourself into, you damn well better wear one too.' And it will reward you immensely if someone says 'nice tie!' Even though you are just as glad when you get a different job and never ever have to fucking wear one again. Stupid as ties are, they do not interfere with your ability to reproduce, tie-wearing people breed. In fact, if everyone in your goddamn environment is wearing one, then not having one, or having a crappy one can hurt your ability to breed. Because people will say to themselves, what the fuck is wrong with that guy? Doesn't he know how to dress? And they will think you are socially defective, which you might very well be, in spite of the fact you are smart enough not to wear one of the neck-chokers, and all the pretty women will mate furiously with the stupid tie-wearing people and leave you out in the cold with no money and the very chilly comfort of being smarter than all the people who won't breed with you.
Other People and sex and bonding are way more important than intelligence and if there is a conflict between the two, the smart money's always on stupidity and sex.
Of course, wearing ties is just one example of a whole host of stupid human behaviors that manage to exist and survive and not prevent people from breeding.
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Of course, there are many more exciting reasons why people are stupid than mere breeding. And since the subject of stupid people fascinates you, you will naturally want to know what they are. Which is why you are going to click over to the next page, even though it's a very very bad idea.....
More Stupid Reasons for Stupidity.... 
Topic: Why are people so stupid?