Knowledge is like a Jenga tower. Some of it rests on other parts of it, and that some is in turn used as a foundation for still more parts going all the way up. You can take some of the foundation away thus making the entire stack wobbly, and trust on the innate cognitive powers of the human brain to work around the gaps, but take away too much and the whole thing comes crashing down.
The problem is that unlike Jenga you don't notice when the whole thing comes crashing down. You think you know when really you don't. This can lead to anything from you being privately misinformed, to looking like a fool in public, to making horrible policy decisions that hurt others.
It can be an entirely benign problem, it can be anything but, there's a wide range of possibility.
As my primary example, much of English literature requires you to understand two things if you are to understand it:
2 The Bible
That's probably one of the better arguments for teaching the Bible in school, just be sure to keep it out of science classes and make sure it stays firmly within literature. We already tend to teach Greek Myth in literature classes (which would be thing three if I'd said three things instead of two) why not the Bible as well?
But this post isn't about the Bible in particular.
If you don't know the concept of a paterfamilias then you don't know Rome. If you don't know Rome then you don't know the New Testament, if you don't know the New Testament then you don't know Shakespeare, and we've now established that you're missing the two things I just said that you need to know if you're going to understand much of English literature.
Before we even get to your lack of knowledge Shakespeare, the lack of knowledge of the New Testament leaves you completely screwed when it comes to something like The Old Man and the Sea. You simply will not get it, at all. What makes you dangerous is that you won't realize you don't get it. You'll think you do and end up interpreting off in all the wrong directions.
A little Learning is a dang'rous Thing;(Alexander Pope, from Essay on Criticism)
Drink deep, or taste not the Pierian Spring:
There shallow Draughts intoxicate the Brain,
And drinking largely sobers us again.
Fir'd at first Sight with what the Muse imparts,
In fearless Youth we tempt the Heights of Arts,
While from the bounded Level of our Mind,
Short Views we take, nor see the lengths behind,
But more advanc'd, behold with strange Surprize
New, distant Scenes of endless Science rise!
So pleas'd at first, the towring Alps we try,
Mount o'er the Vales, and seem to tread the Sky;
Th' Eternal Snows appear already past,
And the first Clouds and Mountains seem the last:
But those attain'd, we tremble to survey
The growing Labours of the lengthen'd Way,
Th' increasing Prospect tires our wandering Eyes,
Hills peep o'er Hills, and Alps on Alps arise!
The point here is, paterfamilias --> Rome --> New Testament --> Old Man and The Sea. If you want to understand the last, you're going to need to know the first.
Feasting customs in general --> Plato --> Rome&Christianity --> anything that happened in the "Western World" after, say, Constantine. So after the first half of the fourth century.
Specifically Jewish customs (including feasting customs) --> parables of the New Testament --> anything involving Christianity ever.
To go in the other direction, these are Bibical references, don't get that and you don't get them:
- Skin of my teeth.
- Time to put away childish things.
- Test everything...
- Zounds (through Shakespeare)
- Am I my [sibling's] keeper?
- Cast the first stone
- Judge not...
- Good Samaritan
- Love your neighbor as you love yourself.
- Do unto others as you would have them do unto you. (Though it has been noted that it appears in some form in every, or almost every, religion.)
- Doubting Thomas
- David and Goliath
- I've heard there was a secret chord
That David played, and it pleased the Lord
But you don't really care for music, do you?
It goes like this
The fourth, the fifth
The minor fall, the major lift
The baffled king composing Hallelujah
(And much of the rest of the song)
- Pretty much anything that uses the name Judas
- City on a Hill
- Lillies of the field
- Salt of the earth
- under a bushel
- according to its kind
Though I will point out that someone using a Shakespeare reference without knowing which play it went with (he thought Hamlet, it was actually Julius Caesar) accidentally told me that I should look to assassination as a way to effect political change. That's the kind of slip ups that can happen if you are missing the Jenga blocks at the bottom of the stack.
There's a reason that when teaching we teach people to read letters before we teach them to read words, words before sentences, and so forth. Knowledge stacks. If we try to teach people to read Moby Dick before the know letters it's going to fail horribly because they'll look at the page and just see a bunch of meaningless squiggles.
That's not particularly dangerous, just stupid. The child is going to know that they have no idea what the fuck Moby Dick is about if they don't know what the letters mean, much less the words.
The danger of failing to recognize that knowledge often requires prerequisites is in things where it isn't obvious that you have no idea what the fuck you're talking about. When you think you know what, for example, "Prodigal Son," means but you don't understand the concept of paterfamilias and are rusty on first century Jewish feasting customs and thus have no idea at all.
When you think you understand logic, but you've failed to learn the basic axioms and are thus throwing around terms you think you know when you really don't.
When you think you understand economics but you don't know that the principle of free markets assumes perfect information which cannot be assured absent regulation (you think the ingredients and nutritional info just magically appeared on the side of the box? You think meat inspectors originally came standard?)
When you think you understand politics but you don't understand the basic facts of how voting works in the region in question.
When you think you understand race relations but you've never stopped to learn what racism is beyond, "White Sheet + Burning Cross."
When you think you understand feminism without ever learning what the word actually means.
That's where the problem lies.
When in your rush to become a self proclaimed expert who knows all about the blocks at the top of the tower you've removed so many of the foundational blocks that the tower collapsed to the ground and far from knowing what you're talking about you're spewing falsehoods that someone at a much lower level than you claim to be can see that what you're saying is utter BS because they actually made sure the blocks in the foundation were there. Their tower may seem shorter in theory, but once you realize it never collapsed where yours did, it becomes clear that they know more than you do. They just know less than you erroneously claim to know.
Knowledge stacks. Skip the foundation and you're not truly going to understand the stuff above it. That's fine if you're aware of it and ok with it. No one can know everything. If you're aware of it and ok with it then there are ways you can deal with it (like scaffolding your knowledge with that of someone who has looked into the basics in detail.) If you don't realize it then you can cause a lot of trouble both for yourself and for others.