There are two very opposite mistakes crackpots and conspiracy theorist often make when they take issue with expert knowledge. The first, when I described here, is to grossly underestimate the intelligence of their opponents, whom they accuse of missing some ridiculously obvious fact. The second is to absurdly overestimate their abilities, usually when they're postulating some kind of elaborate coverup conspiracy.
Consider the fortune-cookie admonishment, sometimes attributed to Benjamin Franklin (who predated fortune cookies, so it's plausible): "Three may keep a secret, if two of them are dead." Why three and two, instead of two and one?
Two people can keep a secret, because each knows exactly whom to blame if the secret gets out. If three people know a secret, and someone talks, the other two have a mystery on their hands, and may blame each other instead of the true leak. And if three people know a secret and one of them ends up dead, the other two may have much more reason to distrust each other, and motive to defect.
The problem becomes exponentially greater the more people are in on the secret, and not just because there is less chance of being blamed for a leak. One person, keeping a secret to himself, will talk to no one. Two conspirators might talk to each other, so there's a chance of being overheard. Three conspirators have three pairings (AB, AC, BC) for secret communications that might be overheard. If you're part of a conspiracy with a hundred fellow co-conspirators you might on occasion talk to about the conspiracy, the opportunities for accidental leaks multiply fruitfully.
So big secrets, involving hundreds or thousands of people in the know, are really hard to keep secret. Insanely, ridiculously difficult. Only in the most unusual circumstances has it been possible to pull this off, and then only for a relatively short time. The code breakers at Bletchley Park, for example, followed extremely strict protocols, but there's more to it than that: they were fighting a war against the Nazis which provided a very, very strong motivation to be careful.
Let us then look at a typical "expert" conspiracy, one fairly near to my heart: that Big Pharma has been covering up a cheap and effective cure for cancer because they don't want to lose the vast profits they earn through less effective treatments.
This is complicated, because there are actually several different secrets that need to be kept here, and "how to cure cancer" is only one of them. They'd also have to deal with a number of secondary secrets about the coverup itself, such as who knows about it, how they're motivating people to keep quiet, and so on. And those are very difficult to cover up, because unlike the codebreakers at Bletchley Park, it's kinda hard to sell "So we can make lots of money while people die" as a worthy motivation, especially when it's from a disease like cancer from which no one is safe. Seriously, if you were a cancer researcher, and you'd stumbled across a potential cure, how much money would you need to keep your mouth shut? And how much would that number change if your friend, your spouse, your child had a diagnosis? Those outrageous profits to Big Pharma would start to get spread pretty thin.
Sure, we can get more sinister, if you want. Maybe The Conspiracy doesn't bribe cancer researchers. Maybe it makes them another offer, one they can't refuse. Something terrible will happen to them, something worse than them or their loved ones dying of cancer, if they let the secret out.
Know what the problem with that is? A threat needs to be credible, and scientists in particular tend to be skeptical people: evidence is their business. So you've got to expect that a few of them are going to need more than just an anonymous "stop it, or else..." letter. Which means that you're going to have to let them in on some of your methods, so they'll believe you mean business when you tell them what will happen. And now you have someone in on a bit of your secret who is not entirely willing to cooperate, someone who will be looking for some possible opportunity to stop you. Because not only are you threatening him and his family, you're also doing it to conceal a valuable boon to humanity he's devoted his entire career to finding.
But those secrets, difficult as they are to keep, are nothing compared to the big one, the primary secret of How To Cure Cancer. Because while maybe you have control over all your fanatically loyal operatives and can contain any situation they're involved with, Nature herself isn't on your team. There are thousands, even millions of people around the globe trying their best to figure out the puzzles of cancer. Some of them are very smart. How are you going to keep them from discovering something, and sharing what they learn? Especially when the entire scientific enterprise is based on publishing and reproducing results, and entire industries exist for just that purpose? They do, after all, publish results, lots and lots and lots of them. The sheer volume of material out there is much more than anyone can process, which is why there are so many scientists collaborating on these monumental challenges. And they're getting their results, not from some library you control, but from experiments and observations they're performing themselves, on real patients and real drugs.
Just try to imagine how staggeringly difficult and complex a task it would be to fool or silence all of these people. It is truly mind-numbingly difficult, probably harder than curing cancer itself. In order to pull it off, you'd have to be superhumanly clever, and ridiculously powerful. And so think about it: if you were that smart and that powerful, why would you even care about the measly profits to be made from selling overpriced therapies that don't really work? If you can coerce hundreds or thousands of brilliant researchers into concealing their research, why can you not just extort trillions of dollars from everyone else? Or heck, why even bother with money, which is just a way of trading with people for what you want. You've got the power to force people to act against their own interests; there's no need to trade with anyone!
Telling a lie, telling a truly convincing and consistent lie, is really hard. People do it sometimes, and yes, there are successful conspiracies and coverups. Of course it's relatively easy for an expert to bluff their way past a completely ignorant lay person. But if you educate yourself a little, and ask intelligent questions, and try earnestly to understand what you're being told, it quickly gets much harder to sustain a consistent lie.
You might hit the limits of your understanding, but if that happens, the humble and proper thing to do is to acknowledge that you really don't know, and reserve judgment, not to conclude that the experts must be lying to everyone. Because while they might well be smart enough to fool you, they're almost certainly not smart enough to fool everyone else.