You'll die if you do that

based on an agenda you were naive to at the time?

This is almost always the case with warning labels (such as the silica gel example), I don't recall ever seeing a warning label that also told you why it was warning you.

This reminds of a recent post over at Meteuphoric: Don’t warn nonspecifically!

Although the packets are labeled "silica gel," they aren't guaranteed to contain nothing but silica gel. In fact, they can contain cobalt chloride or other poisonous things. If you do one day want to eat silica gel, I would recommend getting it from a food- or laboratory-grade source rather than from a packet which says "DO NOT EAT."

There's the whole stranger danger myth, and how most sexual abusers are people you know... there's no razor blade Halloween candy....

One of the stupidest ones I saw, from personal experience, was when the superintendent of my Middle School took over a history class one day to inform us that if a school bully attacks you, and you fight back, you will be suspended/expelled, and the only way to protect yourself from this fate is to passively accept whatever beating the bully offers you by curling into a ball and exposing your back to them.

By the way, kudos for taking an interesting lesson from the biggest moron in all of Portal 2. You have truly displayed that the wise can learn (at least one, but possibly many) thing(s) from a fool.

Tangentially, silica gel packets are sometimes packaged with food. Wild guess: The warning is intended for that context. Your point still stands, though.

The one that I can think of is cracking your knuckles, which supposedly causes arthritis. It's beyond me how cavitation can cause an autoimmune disease, and seems much more likely to me that people are bothered by the sound and settled on a joint ailment as a deterrent. (Studies have shown there is no link, but that cracking your knuckles is correlated with other hand problems. I suspect that's because people with those problems are more likely to be able to / get relief from cracking their knuckles.)

There's a fence in the San Diego Zoo that I leaned on before reading a nearby sign: CAUTION, ELECTRIC FENCE.

This is why you don't eat silica gel.

I'm always mildly bemused by the use of quotation marks on these packets. I've always seen:

SILICA GEL

" DO NOT EAT "

Why would the quotation actually be printed on the package? Who are they quoting?

I don't know if it's on-topic, but "trust your parents" seems to be a pretty good heuristic, evolutionarily speaking. Your parents were successful enough to produce at least one child, and the advice they give will be tuned to your genetics and environment more than average.

An obvious side-effect of this is that you will believe a lot of stupid stuff that your parents tell you.

(Even more off-topic: do people with more siblings trust their parents more?)

Small electronic appliances often have some sort of safety warning tag that includes, in large text, "DO NOT REMOVE." I remember being a bit horrified the first time I saw my mother cut one off a power cord, and only later actually thought through the logic that the hairdryer or whatever it was would be staying in our house, and none of us were going to try to use the thing underwater or something similarly unhealthy.

Thinking about it, a few less savoury examples would be the circumstances surrounding most cases of murder, rape and child molestation. The prototype most people have for these situations tend to involve unknown assailants, but with all three, in the overwhelming majority of cases the crime happens in a social context where the perpetrator is known to the victim.

And extremely common one in my cultural (USA) context is that "being cold" can give you a "cold". According to common wisdom, being out in cold weather with wet hair and no hat will cause you to be infected with a rhinovirus.

The expression encapsulating this is "You'll catch your death!"

When travelling in Eastern Europe, I found a similar attitude towards drafts from a couple locals. The safest was to keep all windows and doors to the outside closed (in a room or car). Opening one portal was frowned on. Two or more (creating airflow) was taboo and would cause sickness.

OK, here is my contribution to the exercise set by the OP:

Although there are important exceptions, such as doxycycline, the vast majority of expired medications are perfectly safe.

Although pharmacies in the U.S. never put an expiration date on the label that is more than 12 months after the fill date, a study done by the U.S. Department of Defense showed that most medications are safe after even 10 years of storage.

It doesn't look edible, or smell appetising, and isn't even especially harmful to ingest in most circumstances. Chances are that if I ever did want to eat silica gel, I'd probably have a damn good reason, and a lifetime of being told to not eat it is an obstacle to that.

People can be stupid. Shockingly stupid. Much like the infamous McDonald's coffee case (which turns out to be much more sensible and fair a verdict when you read the details), I would not be surprised if there were a reason for the warning.

Or do you read the Darwin Awards and think they must 'have a damn good reason' for what they did?

I was convinced via Alcoholics Anonymous (AA) that I would die if I drank again (1) , and was sober for almost nine years. After having become sober early on (17 years old) and after only having used alcohol and drugs in a rather heavy manner for a little over a year, I often wondered whether I was really an alcoholic like is discussed in the Big Book (AA text), I finally decided to experiment.

I had one beer at a comedy club in a circumstance where I knew I'd just have one and self-observe. I noticed the feeling, but did not have compulsions to drink anymore either that night or in the future. I enjoyed the experience by very much believed that if I had good reason, I could still live without alcohol for the rest of my life. It's been about 6 months, now, and I drink on occasion, mostly socially or after a hard day or celebratory occurrence, and it's been going great.

AA actually does say "... and for us, to drink is to die" in several various ways ((Big Book, 4th ed., p. 66 is one example).

I'll simply add that AA-ers would probably respond that I, apparently, was not/am not a true alcoholic and that a real one would have gone crazy into alcohol after an experiment like mine. In any case, they accepted me like a true one and my AA-based boarding school thought I was one.

[1] At least in some form. AA teaches that drinking only has three ends for the Alcholic: jails, institutions, and death. Perhaps I wouldn't have literally died in an institution, but I might have felt like dying.

I don't think I have ever seen a packet of silica gel that didn't have "DO NOT EAT" printed on it, and it's always bemused me.

Perhaps they should make it "DO NOT EAT (serving suggestion)"?

"Don't swim directly after eating".

Getting colds. Getting dirty as kid.

My own way of dealing with electricity is a bit more cautious than necessary. But I like to prepare for some risks. In many cases there is no notable negative effect.

Steven Landsburg says he received such a warning as a child.

(He goes on to discuss belief in belief.)

I have heard so many warnings and horror stories about what happens if you reveal personal information on the internet that I'm overly paranoid about doing so. I get feelings of anxiety when talking about anything tangentially related to myself, even when there's no logical reason not to do so.

Chances are that if I ever did want to eat silica gel, I'd probably have a damn good reason, and a lifetime of being told to not eat it is an obstacle to that.

Or a reason in itself! :D

Do you have any examples [...]

It's not really what sixes_and_sevens had in mind, but Genesis 2:17 fits quite nicely. (Notice that in this story, what God says about the tree turns out to be false and what the snake says about it turns out to be true -- though it must be admitted that the outcome is pretty bad anyway.)

My nephew ate some of the contents of a packet of silica gel in a shoe store while his mother was trying on shoes. He was 3 or 4 at the time. Knowing that silica gel is labled do not eat prompted us to take it seriously and call the poisons board to find out what to do. I took it particularly seriously because I have no idea how it absorbs moisture (eg if it changes volume) and there is usually a lot of moisture in my nephews stomach...

I hadn't heard about the nose picking study so I'm thrilled to hear about it! My toddler does this. I decided not to stop her.

My thought process went something like this:

1) She's not in immediate danger so I'll observe. (It's a different story for me if there are other adults nearby who don't share my inclination to observe first then react.)

2) Children learn by using all their senses. Smaller children learn by putting things in their mouth and tasting them.

3) Boogers, from my memory, are salty and a bit savory. Not foul tasting or bitter which one would expect from inedible or dangerous substances. Also, salt kills bacteria.

4) Children learn to do things either by watching those around them, or by instinct. Since I don't eat my boogers nor does anyone else in our household I assume it's instinctive. I also know from her older siblings that the inclination subsides with age.

5) Will a germ that already has access to the nasal passage do better in the digestive tract? I wouldn't think so. But i do know that children (and adults) do receive certain immunities by ingesting small quantities of otherwise problematic substances. Poison ivy for instance.

However, even with the study I can't be certain that its good idea. First, studies seem to come out on a daily basis contracting each other. Plus, the environment in which my child is growing up in is vastly different from any other generation so instincts can't be relied on. (Hating carseats with a passion is an instinct that I've decided needs to be redirected, for instance.)

Do you have any examples of an authority figure, or a prevailing piece of cultural conditioning, giving warnings of dire outcomes you later discovered to be false, misleading or based on an agenda you were naive to at the time?

For example, the Y2K bug.

This sort of thing is common. The smoke detector principle explains why.

There's a parable about issuing excessive false warnings: The Boy Who Cried Wolf.