When is a little knowledge a dangerous thing?

December 17, 2006 8:47 PM

When is a little knowledge a dangerous thing?

What are examples of situations where trying to do something logically results in an outcome that is worse than the traditional, naive, or intuitive approach? For example, many diets are based on valid scientific knowledge, yet result in nutritional deficiencies that one could easily avoid by following one's natural cravings. Another example is complex regulatory economic policies that are based on elaborate theory, yet in practice perform worse than the much simpler free market. I'm interested when this happens both in scientific fields as a whole and in problems that people try to solve in their own lives. Is there a general name for this phenomenon?

I know that logic and analysis usually fail miserably in the fields of art and human relations, but when are they at a particular risk of failing in the fields where they are supposed to perform best?

posted by lunchbox to science & nature (50 comments total)

Casey Serin comes to mind.
posted by Heywood Mogroot at 8:52 PM on December 17, 2006 [2 favorites has favorites]

This isn't a specific answer, but rather a general one- people who think they understand quantum mechanics (but don't) generally come up with non-intuitive ideas which are completely and totally wrong. Had they just used common sense, they would have realized that, but a vague "metaphysics" notion of QM is a dangerous thing.

The same thing is true in virtually any field; I did a lot of audio engineering in college, and people who knew a bit would start doing things with a very "technical" point of view and ignored what their ears told them....

It seems like their probably should be a general name, and I'll wait curiously to see if someone knows one.
posted by JMOZ at 9:00 PM on December 17, 2006

I always took that to mean the same thing as "I know just enough to screw things up." Or basically thinking you know more than you do, resulting in undertaking tasks you have enough knowledge to start, but not enough to finish. Putting an engine back together takes way more knowledge than taking it apart.
posted by The Deej at 9:13 PM on December 17, 2006

People that know just enough about homemade fireworks & explosives. That's a great example of "knows just enough to be dangerous."
posted by drstein at 9:15 PM on December 17, 2006

Medical decision-making is one area where a little knowledge results in spectacularly bad decision making.

For example, folks have already rushed to condemn post-menopausal hormone replacement therapy for causing breast cancer, despite the fact that other possible explanations for the evidence exist.

Or take the case of congestive heart failure, where a heart weakened by clogging of its coronary arteries pumps blood too weakly. Since the symptoms arise from the fact that the pump is pumping too weakly, let's give adrenaline and isoproteronol and other beta-agonists to increase the pump pressure, right?

Wrong. Those medicines increase mortality over time, both in the setting of acute MI and in chronic CHF. In fact, beta-blockers are beneficial in CHF. The old "the heart is a pump" model simply cannot give enough knowledge to inform good decisions.

Want a third recent example from medicine? How about SSRIs? SSRIs are known to improve the symptoms of depression in adults. The model is that they flood the synapse with serotonin, reducing depressive symptoms. They represent possibly the greatest advance ever in psychiatric care. So let's give them to depressed teenagers, too!

Unfortunately, depressed teens given SSRIs become at much higher risk for completed suicide. The model of the synapse flooded with serotonin being beneficial for depressed folks simply doesn't give enough information to predict the outcome in this situation.

Lest you think that this is all theoretical, the things I've discussed here have been responsible for thousands of deaths that would not have otherwise occurred, or that occurred earlier than they otherwise would have.
posted by ikkyu2 at 9:15 PM on December 17, 2006

You see this all the time with electrical. Some guy changes a light fixture and starts thinking he's an electrician. He moves on to more advanced projects and mixes the ground and neutral on his dryer or fubars the bonding on a subpanel. Next thing you know you go into his attic and see this.
posted by Mitheral at 9:18 PM on December 17, 2006 [2 favorites has favorites]

Electricity is a field where there's a lot of "Hold my beer and watch this" kind of attitude. I've seen guys... both true pros and laymen... do stupid stuff like work on a wire they aren't totally sure is dead while standing on a metal ladder in a puddle of water. Or not realize that you need a certain gauge of wire to handle a certain amount of voltage. Or that friction can be bad for the rubber coating on wires, especially when being pulled through a metal conduit that had pierced against a sharp bulding structural member... the guy inadvertantly electrified the entire steel structure of the building for just one second.

I think a lot of this kind of stuff is just a lack of foresight and lack of appreciation of consequences.
posted by SpecialK at 9:19 PM on December 17, 2006

Actually the first thing that came to mind was people giving medical advice -- or, in some cases, almost any other advice -- on AskMe. And yes, I'd agree that "A little knowledge is a dangerous thing" is speaking more about people underestimating their own ignorance simply because they know one or two things, and not so much entire systems failing because of logic over intuition. It's more about people refusing to admit the limits of their knowledge.
posted by occhiblu at 9:21 PM on December 17, 2006

Mitheral - OHMYGOD. I hope the power to that house got shut off posthaste. Look at the browning on the outer jacket of that romex!
posted by SpecialK at 9:21 PM on December 17, 2006

Thanks so much for the great replies so far! I'll add that one of my main motivations for asking this question is that I tend to "engineer" situations in my life by approaching them as if they were science problems, and have noticed that this sometimes backfires, in the sense that the intuitive/traditional way would have worked much better. I'm trying to figure out whether this just results from random failure of a good strategy, or if there are some other rules of thumb I could use to prevent this from happening.
posted by lunchbox at 9:23 PM on December 17, 2006

Parents who read pop psychology articles in Readers' Digest or "Parade" in the 1970's, then concluded that their children suffered from one or more afflictions or addictions, then decided to act on this knowledge.

One of my own parents was a psych major who never graduated college. I'll leave the possibilities as an exercise to the reader, but I suppose I had a better childhood than I might have. It did seem that our parents never really trusted my brother and I enough to just leave us alone.

How about this: knowing that brushing your teeth is good for you, but not knowing that brushing them too much or with too hard a brush or when the gums recede can lead to erosion of the tooth around the base.
posted by amtho at 9:23 PM on December 17, 2006

I think there's a contradition inherent in your question. Isn't acting without sufficent knowledge by definition the "naive" or "intuitive" approach?
posted by SPrintF at 9:24 PM on December 17, 2006

lunchbox, if you're interested in psychology at all, looking up something like Myers-Briggs or Jungian split between "Thinking" and "Feeling" approaches to processing information might interest you.
posted by occhiblu at 9:26 PM on December 17, 2006

Mitheral, for a second I honestly thought that picture was of a house I used to live in/work on. I guess it feels a little better to know we weren't alone.
posted by wemayfreeze at 9:31 PM on December 17, 2006

Bleach = good cleaner. Ammonia = good cleaner. You'd think mixing the two would be a good idea... but it's super dangerous.
posted by web-goddess at 9:33 PM on December 17, 2006

After many years of observing humanity, I can't think of a single situation where that old saw doesn't apply. Pick any field of human endeavour - from standing upright¹ through to space exploration or nuclear physics² - and you'll find examples of people doing dangerous things (with dangerous and sometimes spectacular results!) through lack of experience, limited knowledge, or wilful ignorance.

Having said that, I think it's the essence of the human condition - that drive to go just that little bit beyond what you know.

¹ Examples range from a child taking their first faltering steps, right through to Funniest Home Videos. And half of YouTube.

² Marie and Pierre Curie come to mind.
posted by Pinback at 9:36 PM on December 17, 2006

How about this: most conscious logic works by representing the world symbolically in words or numbers. Neither words nor numbers can completely represent the entire complexity of any situation, especially if you limit your representation to a reasonable number of words/numbers, i.e., you may be able to describe your relationship with your friend, but it would take a long time to do so adequately and you still wouldn't capture _all_ the detail.

Yet, your intuitive thought (by my way of thinking about it) doesn't depend on words - to me, what makes a solution/feeling "intuitive" is that it _can't_ be easily represented or explained in words, so the basis for it gets glossed over by saying "it's intuitive". However, by avoiding representing everything in words, you can conceive of a lot of details quickly -- maybe using different parts of the brain.

A classic example of this is throwing a ball - if you try to explain exactly how to use your arm/hand/body to get a ball to hit a particular target, it's cumbersome and not very helpful. But if someone competent just throw the ball, his brain learns how to automatically "does it" and figures out the timing, force, and angle needed - non-verbally and quickly.

You might argue that this example is unrelated, but it's related in this: there are indispensible details to solving the problem of "how to throw" that would be difficult to represent verbally. Yes, you can use physics to model it, but it takes much longer than just throwing the ball, and people were throwing things successfully long before the physics was figured out.
posted by amtho at 9:40 PM on December 17, 2006 [2 favorites has favorites]

I include myself in this:

Google search box ≠ research

posted by rob511 at 9:45 PM on December 17, 2006 [1 favorite has favorites]

If you have a little bit of flying experience, you might think you know how to recover from spin, but you'll only end up in a worse spot. It's difficult to describe without a model or hand gestures, but failure to break the stall (and restore lift-generating angle of attack to the wings and control surfaces) and/or premature use of ailerons will only aggravate the stall further, sometimes into a self-reinforcing situation where recovery is impossible (i.e. maximum control input cannot break the cycle of yaw, roll, pitch interaction)

And even if/when you know better, your gut instinct is the wrong thing and you have to think around your instinct and wrestle control back to your conscious mind.

A more common aviation example: when flying at low speeds the usual control input for altering altitude (the elevator) is used to control airspeed, and the usual control for airspeed (the throttle) is used to control altitude. Thus, in landing configuration (or slow/low flight of most kinds) pulling up will actually cause you to lose altitude. Again this is the kind of thing you'd screw up if your only flying experience was from a PC simulator game or something.

I hope these help, however arcane they may be.
posted by KevCed at 10:03 PM on December 17, 2006

Feynman called this "cargo cult science", and talked about it in several of his books, including "Surely You're Joking, Mr. Feynman". Basically, it was a reference to some (South Pacific?) indigenous island tribes. During WW2, they saw military bases airstrips that brought what they saw as wealth to the island. When the war was over and the soldiers left, they built their own faux airstrips complete with control towers and the guys on the runway with the headphones and batons.

Obviously (to us, anyway) this didn't work. But it's the same sort of principle as what you're talking about, and it happens all the time to otherwise intelligent people. (Or perhaps one could argue that true intelligence is the ability to recognize when you're out of your league ...)
posted by spaceman_spiff at 10:06 PM on December 17, 2006 [1 favorite has favorites]

By themselves, small amounts of knowledge are seldom dangerous. They become dangerous when combined with immature desires, and unanticipated situations. If you only know a little bit about flying, you can pass a check ride for a private pilot's license, and rent planes like those in which you qualified. You can then take up your sweetie, and all your pals, and amaze them with your newly licensed powers as a sky god.

But the first patch of violent clear air turbulence you hit at 8,000 feet on a summer day will remind you that you are in the air by the grace of Bernoulli, and the simple goodwill of hourly production workers in Cessna's Witchita works, and the dour skepticism of taciturn men with airframe and powerplant certifications, that conducted your aircraft's last maintenance and required inspections. And when Mother Nature has thrown you about, and shown you and your passengers what a mote in God's eye you all, collectively, comprise, she may free you to land in one peice.

Or, not.
posted by paulsc at 10:20 PM on December 17, 2006 [2 favorites has favorites]

Anytime someone knows enough to know that they should/shouldn't do something without understanding the reason(s).

Marie Curie.
shoe store fluoroscopes

Oft times computer users serve as a good example. For example, people who know about the Window's registry and think they understand it well enough to "speed up" their PC. Or people who manage to get Gentoo running and think they are Linux gurus.
posted by Grod at 11:19 PM on December 17, 2006

English speakers learning Spanish and trying it out on native speakers. American women will add "ada" to the approximate ends of many English words to form adjectives, but this is a disaster when trying to work out "embarassed" because you end up with "pregnant." And so with adding "a" to the ends of English nouns to get Spanish nouns - magic - until soap becomes "sopa" and you're asking for soup instead of hygiene. Whoops!

Also, conjugating verbs makes for some good jokes sometimes.

This goes the other way too. I live in the greater Miami area, closer to Ft. Lauderdale. We have a large immigrant community and a lot of native English speakers here are frustrated that the new people don't "learn English right." (Don't get me started on the double standard there.)
posted by bilabial at 2:21 AM on December 18, 2006

Another way to think of this is how my dad claims his office is organized (engineer at DOD). There are 4 types of people.
Type 1: Smart Eager people.
Type 2: Smart Stupid people.
Type 3: Dumb Stupid people.
Type 4: Dumb Eager people.

Type 1's are the people you want to have in underling positions, because they can and want to do things on their own. Type 2 people are the people in charge because they get all their information from the type 1s. Type 3's are basically the grunts of any organization. And Type 4's? Well, they're the ones who get everyone else killed.
posted by sperose at 2:58 AM on December 18, 2006

The MMR vaccine and autism.

Those who know nothing get their children vaccinated. Those who know a little (via the Daily Mail, "Dr" Gillian McKeith and others) do not, placing them at significant risk.
posted by alby at 3:15 AM on December 18, 2006

lunchbox - from a Psychology point of view I would recommend "Descartes' Error" by the neurologist Antonio Demasio. The book explains that those who have experienced damage to areas of the brain that deal with the processing of emotions have great difficulty in making rational decisions. His proposal is that it is precisely our "intuition" that is essential for making decisions when there is either too little or too much information. Demasio would probably claim something like " A little knowledge is a dangerous thing when you don't have any gut feelings about the subject matter".

Psychologists would also say that a little knowledge can be particularly dangerous when it deals with a subject for which there is a cognitive bias. This includes many issues relating to quirks of visual perception, the desire to do do the right thing in a social setting or practically anything involving the judgement of statistical probability.
posted by rongorongo at 4:57 AM on December 18, 2006

When one doesn't know what 'little' is.

In many fields there are recognized specialists or courses of training, and it is easy for most people to know that their own knowledge falls short. For example, most people in reality recognize whether they possess medical knowledge or not. There are medical qualifications that make you a physician, and in many jurisdictions, you cannot call yourself a physician until you have said qualifications.

In other fields, people can easily think that the little knowledge they have is all you need. For example, when it comes to fixing computers, while there are computer courses of varying sorts (from basic to advanced), anyone can call themselves a computer technician. Not everyone will know the difference until it's too late.

None of this stops people being idiots.
posted by blue_wardrobe at 5:12 AM on December 18, 2006

If I start thinking my way through a complicated problem I've learnt to stop and get help when I brush aside even the smallest unresolved question or concern, because that means I don't fully know what I am doing and I'm not qualified to be doing it alone.

I see this over and over in any complicated endeavor. People driving a car and not properly understanding the flow dynamics (gee, I'll get in this already slow lane with too many people in it... nothing bad will happen!), anything to do with computers, managers speaking from the gut rather than their brain and not realizing as much, anything to do with chemicals including home cleaning supplies as web-goddess said, etc.

Of course I can't always get help or see when others need it, but even knowing the weak spots is better than where I was before.
posted by jwells at 5:34 AM on December 18, 2006

KevCed's point about flying applies on a smaller scale to driving. If all you know is how a car's controls work, you'll be fine on a smooth flat road but absolutely fucked in a skid. "Oh," you say, "turning the steering wheel makes the car change directions! I'm veering uncontrollably to the left, I'd better crank the wheel to the right." And then, a minute later, "Oh! Braking makes the car stop! I've lost control, I'd better hit the brakes hard before I run into something." And then instead of just skidding a little you're spinning out in the middle of a highway.

Similar things happen to people who get stuck in mud, start hydroplaning, or have to drive on tall hills for the first time. You need to know the controls and some of the physics involved to drive safely. Just knowing the controls is indeed a dangerous thing.
posted by nebulawindphone at 6:27 AM on December 18, 2006

Mitheral

I'm not certain what I'm seeing there beyond extremely shoddy, disorganized wiring.
posted by The Confessor at 6:34 AM on December 18, 2006

Modern mainstream medicine seems to be doing a pretty good job of dealing with a lot of disorders, but there are others where it may well be dropping the ball (depending on who you talk to). These include diabetes, obesity, heart disease, fibromyalgia, and anxiety, just to name some off the top of my head. You will find plenty of people out there who've had better luck treating these disorders with alternative or traditional approaches than with the latest treatments backed by research and prestigious medical authorities. Now, in many of these cases, you can also find a book or web site arguing that a given non-mainstream approach in question is based on some theory or set of facts. (And of course there's always someone else arguing that the theory is incorrect or that the facts are misinterpreted). However, it's been my experience that most people who use them simply try things they've heard about (which is really just another way of saying "tradition") or that seem likely to help ("intuitive") and don't worry too much about the theories and facts. They judge the results using good old fashioned trial-and-error.
posted by Clay201 at 6:35 AM on December 18, 2006

By themselves, small amounts of knowledge are seldom dangerous. They become dangerous when combined with immature desires, and unanticipated situations.

I agree with amtho that it is a deeper problem than that. Animals do incredibly complex things without analysis. We have developed the ability to analyze (literally, to tear apart), and while this allows us to better understand many parts of the whole, it does not necessarily give us full comprehension of the intricate interactions and connections of the system. this thread about the common cold is a decent example of the way 'folk knowledge' is roundly dismissed for a simpler theory (colds are caused by a virus) without noticing that it has got to be more complicated than that (not everyone in the presence of a virus becomes sick).

Hegel's philosophy could be referenced here - the idea that first there is a blind unexplored assumption; this is strongly rejected by the rational logical movement; but the truth turns out to be a synthesis, which in essence confirms the original thesis but with a deeper understanding of the mechanism (eg, for the cold example we could say a-being cold & wet causes colds, b-no, it's a virus, and it's silly to worry over coats or dry hair; c-it's a virus, but it only becomes active in a compromised immune system, which can be brought about by being cold & wet. In this example, mom's advice turns out to be right, even though the mechanism is technically what the rationalists said it was). Of course, Hegel was writing about complex social systems, but his basic philosophy is focused on 'what knowledge is', and he makes it very clear that the segregated logical stage is a stage before the holistic understanding, and often results in disaster (the french revolution is one example he cites).
posted by mdn at 6:36 AM on December 18, 2006 [1 favorite has favorites]

Computer programming.

I'm a professional Actionscript programmer. AS is Flash's programming language, and it's very hard to find people who know it well. Computer Science people think of Flash as a toy, so they don't bother learning it. So most of the people who "learn" AS are designers. They tend to learn a command here and a command there, and they cobble things together without really understanding how anything works. After a while, they find they've created a huge, tangled mess (spaghetti code) that will topple if someone breathes on it.

This is usually where I come in. Some company hires me because they want to add one tiny feature to the application, and when their "programmers" try to do it, the application breaks. I generally wind up having to rebuild the entire thing from scratch -- just so I can add the tiny feature on a solid foundation.

Most programmers have stories like this.

I also teach programming courses for designers. At the beginning of the class, when I ask them about themselves, they usually say, "I don't really want to learn Actionscript. I just want to know enough to be able to tweak code to make it do what I want." So there's an example of people actually WANTING to learn just enough to be dangerous.

To be fair, I totally understand where they're coming from. They got into this game to be designers, not programmers. But a tight economy forced them to wear multiple hats. They're trying to spend as little time as possible wearing the programmer hat. And mini-languages, like HTML (along with WYSIWYG editors, like Dreamweaver), have made them believe that it's not really necessary to learn a language thoroughly in order to use it effectively. Unfortunately, I have to explain to them that this approach won't work with a real programming language.
posted by grumblebee at 6:42 AM on December 18, 2006

I'd say a big one is the seeming eagerness to accept someone's declaration they are a religious expert or some sort of authority (even as simple as "Christian" or "Muslim") yet not use this same automatic credibility when trying to discern whether what they're saying as actually true, such as actually looking it up in the bible or qu'ran to verify it.

A very significant number of scriptural qualms come from the abundance of unverified speculative rationale (or otherwise lockerroom-banter level of accountability) without actually verifying where what was said as actually in the scripture in question, or whether the speaker claiming to know something is actually an authority or not -- and then adopting that as part of a very real belief system!

And to a similar regard, perhaps the automatic mass-labeling of a particular religion based on the acts of the few outspoken protesters (insert the "God hates fags" Christian weirdos, or the obsenely-jihad-frenzied Muslim own-agenda-pushers here) that newsreporters decide to write stories about, instead of the other 2.38 fillion dillion who red-in-the-face believe precisely the opposite and point to you exactly where it says the opposite but are unable to defend themselves in exactly the same forum for fairness.
posted by vanoakenfold at 6:53 AM on December 18, 2006

Teaching. A lot of people assume that, with a degree, they become great teachers. After teaching as a grad student for six years and faculty for five, I am discovering that I am competent when compared with my peers, but completely freaking clueless when it comes to really, really effective teaching that meets the needs of everyone in the room and doesn't suck up 80 hours a week. Any humanoid can give out scantron tests and lecture, and get acceptable student evaluations. Real teaching, where students grasp concepts, retain the knowledge, and enjoy the process, is bizarrely complex and difficult, especially if you try to drag it out of the realm of romanticized narratives, intuition, and anecdote.

Relationships probably fall into the same category.
posted by craniac at 7:18 AM on December 18, 2006

The standard joke among programmers at my company is the question, "Can't you just add an 'If/Then'?" We hear this from nontechnical coworkers, upper management, etc. all the time. People who have a tiny smidgen of programming knowledge can be very dangerous to the morale/tempers of the technical staff, not to mention to the status of the project. Thank goodness these people don't actually have access to the code.

And on a related note from a previous job, sales people who sell bespoke software. They know just enough to invent and promise great new features, without knowing what it will take to implement those features (or whether the features even possible, never mind budget or deadlines or the rest).
posted by vytae at 7:50 AM on December 18, 2006

I'd say a big one is the seeming eagerness to accept someone's declaration they are a religious expert or some sort

I'm continually embarrassed by my fellow atheists' belief that they understand the major world religions. They generally don't. They haven't read the Bible; they haven't read anything by major religious thinkers.

To them, religion means "the stuff my Mom and Dad made me say and do when I was a kid." Of course, many theists also don't understand the foundations, documents and history of their own faiths. But there have been and are serious, scholarly, brilliant theists. They have already thought out and dealt with most mundane atheist objections. Atheists (and many theists) don't read this scholarship, so the "debate" stays on the moronic level of "Can God make a rock so heavy that He can't lift it?"
posted by grumblebee at 7:52 AM on December 18, 2006

"whether the features are even possible"
posted by vytae at 7:52 AM on December 18, 2006

I have a friend who is a house painter. Sometimes he bids out smaller jobs on an hourly basis. When people ask his rate, he tells them "$25 and hour - $50 if you help."
posted by Mister_A at 8:26 AM on December 18, 2006

Ack!! AN hour, sorry.
posted by Mister_A at 8:26 AM on December 18, 2006

The Confessor writes "I'm not certain what I'm seeing there beyond extremely shoddy, disorganized wiring."

Exactly. This is kind of an extreme case but to a lesser degree I used to see that kind of thing all the time doing service work. Dangerous DIYers (and sloppy professionals) do stuff like leave cover plates off; fail to install knockout covers; just string wire along the attic floor instead of stapling it; get wire too close to heat sources without shielding it; put multiple wires under the same lug etc. etc. Stuff that "works" but creates either an immediate hazard or potential hazard in the right circumstances.

Not installing knock out covers is my favourite ignorant homeowner/sloppy professional mistake. 999 times out of a 1000 nothing bad happens. But when Murphy strikes and a mouse makes it's way thru the hole and shorts out the mains or an outlet has two wires under the screw instead of being pigtailed maybe the house burns down. All for the want of a 15 cent plug or a six inch piece of wire and a marette.
posted by Mitheral at 8:32 AM on December 18, 2006

I administer computer networks. Recently a user with very limited computer experience connected their camera to their PC, and attached 400MB of xmas party photos to a message, and sent it to everybody in the company. It brought their aging mail server to its knees.

If they had less knowledge, they would have worked with someone to upload the photos to a shared folder, and done it right. They did, however have enough knowledge to create the email. They didn't know enough to know it was the wrong thing to do in their case.


What a nightmare that was.
posted by upc_head at 9:01 AM on December 18, 2006 [1 favorite has favorites]

Mitheral

Ah! I thought I was supposed to be seeing the results of that shoddy wiring job already in progress.
posted by The Confessor at 10:40 AM on December 18, 2006

Great question.

I was reading once about this lady who, as a sort of hobby, takes care of fallen birds, especially hummingbirds. People find one that fell out of its nest, and they typically call the zoo; the zoo tells them to call this lady.

Well, this lady says that lots of times, people find a baby hummingbird, and they think "hummingbirds eat sugar water, right? So I'll just feed this one some sugar water until I can find some help."

Turns out, baby hummingbirds have no idea how to drink properly, so the sugar water gets all over them, their wings rot, and they die.
posted by Brian James at 11:43 AM on December 18, 2006

I see it a lot with regard to citizens misinterpreting environmental legislation, especially the Wetlands Protection Act. I have encountered people who destroyed wetland buffers in attempts to do something to "protect" the wetland.

I've also seen it quite a bit with regard to invasive species, e.g. someone who chops up all the milfoil in their pond to destroy it, not knowing that they are facilitating its spread.
posted by nekton at 12:01 PM on December 18, 2006

Slight snark, but that saying could be considered a case in point.

In the venue of criticism, exposure to various bits of critical theory (or at least to their theoretical lexicons) can definitely 'intoxicate the Brain', and needs to be worked out of one's system.

A little learning often brings with it a false sense of coherence, or misapplication of limited techniques and/or principles to inappropriate situations.

Perhaps the more interesting cases are ones where it doesn't apply, and limited learning (and I'm going to retain Pope's distinction between learning and knowledge here). An example might be foreign languages, where it's relatively difficult to say something horrifically inappropriate when you lack the vocabulary, and you're always well aware of what you can't say.
posted by holgate at 1:00 PM on December 18, 2006

Chemical synthesis
posted by Pressed Rat at 2:24 PM on December 18, 2006

KevCed's point about flying applies on a smaller scale to driving. If all you know is how a car's controls work, you'll be fine on a smooth flat road but absolutely fucked in a skid. "Oh," you say, "turning the steering wheel makes the car change directions! I'm veering uncontrollably to the left, I'd better crank the wheel to the right."

But if you yaw past 90 degrees, you had better turn the wheel in the other direction. Here's a good example.

Fishtail under braking (sloppy downshift) at 7 sec mark demonstrates your point. Losing tail at 27 sec mark demonstrates mine.

(Yes it's me -- self-link, but very relevant, and I can't resist sharing at every opportunity. And I swear to you this concept never occurred to me until I found myself sliding backwards into the braking zone, heh)

And then, a minute later, "Oh! Braking makes the car stop! I've lost control, I'd better hit the brakes hard before I run into something."

Yep, in the big slide, I (counter)counter-steered correctly, but the car didn't correct until I let off the brakes to let the tires roll. Good times!

Watch rally/dirt drivers on tv, and you'll see them do this to recover when they lose the tail. (Never noticed it before I did it myself!)
posted by LordSludge at 6:24 PM on December 18, 2006

The big one: when you try to be your own lawyer.
posted by KRS at 6:36 PM on December 18, 2006

Another example is complex regulatory economic policies that are based on elaborate theory, yet in practice perform worse than the much simpler free market.

I think that your own example is a case of assuming a complete knowlege, but not having enough knowledge to argue the case, which rests on dogmatic faith. Your example assumes that a free market is both simple and inevitable outside of government regulations. This is naive.

I would argue that most regulatory policies are usually justified in theory, the problem being easily identified in practice (such as toxic pollution or slavery). Yet the best solutions are often gamed, compromised and corrupted by the very complex free market where might makes right, and thus the public might must be demonized by those who compete against the public's interests. Those who think that a truly free market isn't directly supported by idealistic government policies, banking, and enforcement are guilty of possessing a little knowledge in a very dangerous way.
posted by Brian B. at 1:29 PM on December 21, 2006