When we are 10 years old, we understand religion – how the world was created, who did the creating, and how it affects us today. When we are 15 years old, we understand our place in the world – who we ought to be, how we ought to act, and how to exert our will on the world around us. And by the time we reach 25 years old, we believe that we are able to understand the merits and faults of nearly every facet of society. The morality of abortion? Obvious. The solution to world hunger? Clear. I can explain nearly everything anyone encounters in the world. And for any new surprises in life, such as new scientific discoveries or new trends in human culture, I can always figure out pretty quickly a few words to say about who is to blame for it, how to explain it, or why it doesn’t matter. Universe - solved.
Feels pretty darn good, doesn’t it?
It’s also ridiculous. Yet, it’s kind of what we all think is true of ourselves and our beliefs.
Why we do it
Who we are personally is not entirely to blame for this behavior – partially it is the way we learn. When a baby learns to walk, he learns by doing. If he starts to walk in a way that is “wrong”, something bad will happen. He’ll realize he’s not able to do everything daddy does when he walks, or he’ll fall and get hurt. It’s the same way with learning most simple things. Once you start to go from the simple actions to the more complicated ones, though, the reality is that you may be allowed to live your entire life believing something which is stated as being obviously false given only very reasonable assumptions.
We also tend to believe what we feel is most likely to be true, but in doing so, almost always lost sight of the level of certainty that we ought to have. We think of certainty comparatively, and very seldom objectively. That's why things like the morality of abortion seems obvious. Were abortion not an issue, would this statement
"two reprodcutive cells come together count as a human being with every legal right and moral obligation that every other fully formed human being has - but only once they come together - not beforehand - and really, this means you better be aware of your actions conseqeunces on a cellular level or you may be committing homicide right now"
be believable with some form of proof or demonstration or reasonableness? Of course not! In this same sense, would the statement
"there is an age x, at which an unborn fetus magically transforms from being nothing more than a bit of a woman's body to being something every bit as respectable as you or I - so go ahead and play tennis with an x-1 month old fetus, but after that, it's a real being"
be believable without proof? Once again - of course not!
But given the two options, everyone picks one which suits them best, promptly forgets how little we know about the human reproductive process, and then is therefore capable of asserting their belief as though it were obviously and demonstrably the way things are.
Why it’s detrimental
Initially, there are two obvious points to make which I've lightly touched on above. For the idealist - overstated confidence makes you believe crazy things are real. For the socialite - this confidence also at best creates situations in which you are uncomfortable or incapable of acting reasonably. This means that, generally, there are things you just never talk about with friends who should be held in more confidence (because the unfortunate truth is that we favor confidence in beliefs over confidence in people) - things like religious convictions, politics, beliefs on morality. And when in situations where these things are being discussed (especially by those whose confidence in their beliefs are at more reasonable levels), you cannot possibly act reasonably.
But there's more - if you think about how credit cards are offered, how banks structure their fees, how advertisements work, how con artists operate - people who are overconfident can be endlessly exploited into situations where they stand to lose financially, emotionally or otherwise. And really, even if only one of the ways you are weakened by overconfident is seen as "valid" - what benefits does overconfidence really provide? A false feeling of stability?
How to Be More Reasonable
The first part is easy. It’s in the introduction. Just remind yourself you don’t know everything – you don’t have to and even if you felt you did, you can’t. The trick is meaning it this time. There are a broad category of things that people can only really guess about – and someone else’s guesses about what is true are about the least useful things you can think of.
Here’s a simple rule of thumb. If it seems like a lot of people disagree about something, and it seems like only one of the answers appears reasonable – then obviously you don’t really know much about the topic at hand. People don’t take incorrect positions just for fun. If the solution to something seems simple, yet people disagree about it, it’s probably actually complicated – maybe even complicated enough that we don’t want to take the time to understand it.
AND THAT’S OKAY. There’s no quiz at the end of life where if you don’t understand the intricacies of the debate between religion and science over how the universe began, you’ll get an “F”, get slapped on the wrists, and be forced to repeat your last life again. At least, I don’t know of any quiz like this. Remember our introduction. You don’t know everything, and you don’t need to.
So, having identified an issue you’re ignorant on either:
1. Admit ignorance and omit yourself from the debate, or
2. Provide yourself with a theory, and then approach that theory as a theory until you can explain beyond the shadow of a doubt. Note that this means explaining not only to yourself (who has no reason to doubt your theory), but to those who *would* actually doubt you – to those who already disagree with you.
I'm already going to get hell for using abortion, so I may as well stick to that path in illustrating this approach here. There's nothing wrong in saying that I lean pro-choice, as long as I admit that this is absent a large amount of information and experience (both not being a woman and not remembering the experience of being a fetus), and that people can have other theories, which I do not have to vehemently disagree with. In this way, I can be (and probably am) wrong. Personally, I have a theory that the "soul" is a real concept and that the "sudden humanness" of a fetus can be attached to the point at which the soul is completely attached to the person. That sounds ridiculous, and I admit that. But it's a theory - so it doesn't have to be right, it just has to be plausible.
Conclusion
Humanity is knowingly ignorant, but constantly disbelieves its ignorance until proven otherwise (and in doing the proving, it allows itself to reassert its claim by adjusting the set of what is "known" - i.e. humans knew everything when we believed the world was flat, and having now understood that it is round, we continue to know everything). This is how it is and how it has been since the beginning of time. These are things we likely cannot change. The human mind is too established and follows too strict a path to get where it must get in modern society. Our goal, then, should not be to change how we are, but to accept how we are created, understand the implications of how we are, and do our best to live with them. We are ignorant, and we won’t truly accept that we are ignorant. But if we can accept that this is the reality of the situation, we can keep our eyes open, keep our heads high, and do what humans do best – what humans were freaking born to do: to create, to adapt, and to learn - without allowing ourselves to be sidetracked by overconfidence.
TL;DR - I lost interest after the OP admitted he was kind of dumb. I probably know better than he does already, anyway.