Here’s another provocative Paul Graham essay, this one about heresies. Excerpts:
Have you ever seen an old photo of yourself and been embarrassed at the way you looked? Did we actually dress like that? We did. And we had no idea how silly we looked. It’s the nature of fashion to be invisible, in the same way the movement of the earth is invisible to all of us riding on it.
What scares me is that there are moral fashions too. They’re just as arbitrary, and just as invisible to most people. But they’re much more dangerous. Fashion is mistaken for good design; moral fashion is mistaken for good. Dressing oddly gets you laughed at. Violating moral fashions can get you fired, ostracized, imprisoned, or even killed.
It seems to be a constant throughout history: In every period, people believed things that were just ridiculous, and believed them so strongly that you would have gotten in terrible trouble for saying otherwise.
Is our time any different? To anyone who has read any amount of history, the answer is almost certainly no. It would be a remarkable coincidence if ours were the first era to get everything just right.
Let’s start with a test: Do you have any opinions that you would be reluctant to express in front of a group of your peers?
If the answer is no, you might want to stop and think about that. If everything you believe is something you’re supposed to believe, could that possibly be a coincidence? Odds are it isn’t. Odds are you just think whatever you’re told.
The other alternative would be that you independently considered every question and came up with the exact same answers that are now considered acceptable. That seems unlikely, because you’d also have to make the same mistakes. …
If you believe everything you’re supposed to now, how can you be sure you wouldn’t also have believed everything you were supposed to if you had grown up among the plantation owners of the pre-Civil War South, or in Germany in the 1930s– or among the Mongols in 1200, for that matter? Odds are you would have.
Back in the era of terms like “well-adjusted,” the idea seemed to be that there was something wrong with you if you thought things you didn’t dare say out loud. This seems backward. Almost certainly, there is something wrong with you if you don’t think things you don’t dare say out loud.
What can’t we say? One way to find these ideas is simply to look at things people do say, and get in trouble for. 
Of course, we’re not just looking for things we can’t say. We’re looking for things we can’t say that are true, or at least have enough chance of being true that the question should remain open. But many of the things people get in trouble for saying probably do make it over this second, lower threshold. No one gets in trouble for saying that 2 + 2 is 5, or that people in Pittsburgh are ten feet tall. Such obviously false statements might be treated as jokes, or at worst as evidence of insanity, but they are not likely to make anyone mad. The statements that make people mad are the ones they worry might be believed. I suspect the statements that make people maddest are those they worry might be true.
Read the whole thing. I am reminded of a fascinating symposium on Edge.org, the science site, in which scientists were asked to state what was their “dangerous idea,” defined as “an idea you think about (not necessarily one you originated) that is dangerous not because it is assumed to be false, but because it might be true.” What makes the idea dangerous, it seems to me, are one, possibly two, things: 1) to express it would put one in danger from his peers or the wider community, and/or 2) if everyone came to believe it, bad things would happen.
I don’t speak of “dangerous ideas” in scare quotes. There really are dangerous ideas. The late critic Roger Shattuck wrote a terrific book a few years back called “Forbidden Knowledge,” which explored the history and contours of dangerous ideas. There really are good reasons to make certain ideas taboo. But there are always more ideas that are taboo than there are ideas that ought to be taboo. Graham again:
So if you want to figure out what we can’t say, look at the machinery of fashion and try to predict what it would make unsayable. What groups are powerful but nervous, and what ideas would they like to suppress? What ideas were tarnished by association when they ended up on the losing side of a recent struggle? If a self-consciously cool person wanted to differentiate himself from preceding fashions (e.g. from his parents), which of their ideas would he tend to reject? What are conventional-minded people afraid of saying?
Graham advises, perhaps surprisingly, that keeping a free mind means keeping tight rein on your big mouth:
The most important thing is to be able to think what you want, not to say what you want. And if you feel you have to say everything you think, it may inhibit you from thinking improper thoughts. I think it’s better to follow the opposite policy. Draw a sharp line between your thoughts and your speech.
I would like to poll you readers and ask for your dangerous ideas. I’m going to be selective in posting them. Be thoughtful when you write, and do your best to explain why you think it might be true, and why it’s dangerous (if you need to explain it).
As an aside, I think the existence of heresies within our political parties, and (especially on the Right) the existence of a loud and forceful brigade of enforcers who punish heretics, is largely responsible for the lack of imagination and constructive, creative thought in American politics. All those Republican presidential candidates who never, ever will consider a tax increase, no matter what, are terrified of Torquemada. To Torquemada, though, this looks like simply holding the line on an important principle. Then again, political parties are not churches. As a religious believer, I think churches are right to hold the line on heresy. Political parties? No.
Say, I’m going down to Georgetown today for an all-day conference. Don’t know how often I’ll be able to check in on this site to approve comments. Please don’t think I’m ignoring you if it’s a while before yours posts.
UPDATE: To expand, let me talk a bit about conditions under which certain ideas (including mere information), even true ones, can be dangerous.
A few years ago, I was at a journalism conference overseas attended by reporters from the US, Western Europe, and countries in the Global South. We Western reporters were conditioned to believe that if you have truthful information, you should report it, and let the chips fall where they may. Yet our colleagues from India said that their newspapers routinely withheld religious information from reports of inter-religious violence (e.g., a Muslim man suspected of attacking a Hindu woman) — even though such information was often vital to a more complete understanding of the story. Why? Because they live in a country in which religious passions can quickly become inflamed, leading to mob violence and murder. In their country, this was not an abstract threat. They lived with it every day. It was easy to see, therefore, why these journalists engaged in a kind of self-censorship that would have been viewed disreputably in the West.
Or would it have been? Many US media outlets have a policy of not identifying race or color of a criminal suspect, lest it feed into stereotypes. This is in most cases indefensible, particularly when a suspect in a violent crime is on the loose. Yet it is routine. Similarly, the US media in general has avoided critical reporting on the radical leadership of many mainstream American Muslim organizations. My view is that they have internalized the desire to protect ordinary Muslims from persecution — a laudable goal, but one that is, I think, unjustified in this country. Ten years after 9/11, most Americans still do not understand how powerful the radical Muslim Brotherhood is within the ranks of the US Muslim leadership. And for that, I blame non-Muslim American journalists.
Nevertheless, I concede that the Indian journalists at my conference are correct, and that there are times when the responsible thing to do is to withhold information, or to decline to express ideas, when the harm in doing so can outweigh any good that could come of it. It is difficult, even impossible, to come up with a foolproof method for deciding when this is the case. As Paul Graham avers, we often tell ourselves (and others) that we are forbidding certain ideas (by which I mean to include the publicizing of information) for the greater good, but what we are really doing is identifying “heresy” to protect the interests of individuals or groups. In the Church sex abuse scandal, I believe that bishops who fought tooth and nail to keep the crimes committed against children private were, in many cases, proceeding from what they truly thought were laudable motives (e.g., to protect the image of the Church and, therefore, the faith of common people in its integrity, the loss of which — the faith, I mean — could be deleterious to their salvation). But as we now know, what they were really doing was protecting themselves and the clerical class from the justified scrutiny of others — and, in so doing, allowing monstrous crimes to continue unchecked.
The difficult thing about this is that both things can be simultaneously true. That is, bishops were not necessarily wrong to seek to keep these horrible things secret — not at first. Not everything that can be said should be said. Had they used this silence as a cover to effectively deal with the crisis, it would have been justifiable. But they did not; they used it as an excuse to avoid dealing with the problem. Without sunshine, the rot grew.
We can see that in retrospect, of course, but it is devilishly difficult to understand this in real time. It is very hard to know which taboos ought to be observed, because they serve a morally justifiable function, and which ones are unsupportable, and should be abandoned.