I have so far distinguished between belief as anticipation-controller, belief in belief, professing and cheering. Of these, we might call anticipation-controlling beliefs "proper beliefs" and the other forms "improper belief". Proper belief can be wrong or irrational, as when someone genuinely anticipates that prayer will cure their sick baby. But the other forms are arguably “not belief at all.”
Yet another form of improper belief is belief as group identification—as a way of belonging. Robin Hanson uses the excellent metaphor of wearing unusual clothing, a group uniform like a priest’s vestments or a Jewish skullcap, and so I will call this “belief as attire.”
In terms of humanly realistic psychology, the Muslims who flew planes into the World Trade Center undoubtedly saw themselves as heroes defending truth, justice, and the Islamic Way from hideous alien monsters a la the movie Independence Day. Only a very inexperienced nerd, the sort of nerd who has no idea how non-nerds see the world, would say this out loud in an Alabama bar. It is not an American thing to say. The American thing to say is that the terrorists “hate our freedom” and that flying a plane into a building is a “cowardly act.” You cannot say the phrases “heroic self-sacrifice” and “suicide bomber” in the same sentence, even for the sake of accurately describing how the Enemy sees the world. The very concept of the courage and altruism of a suicide bomber is Enemy attire—you can tell, because the Enemy talks about it. The cowardice and sociopathy of a suicide bomber is American attire. There are no quote marks you can use to talk about how the Enemy sees the world; it would be like dressing up as a Nazi for Halloween.
Belief-as-attire may help explain how people can be passionate about improper beliefs. Mere belief in belief, or religious professing, would have some trouble creating genuine, deep, powerful emotional effects. Or so I suspect; I confess I’m not an expert here. But my impression is this: People who’ve stopped anticipating-as-if their religion is true, will go to great lengths to convince themselves they are passionate, and this desperation can be mistaken for passion. But it’s not the same fire they had as a child.
On the other hand, it is very easy for a human being to genuinely, passionately, gut-level belong to a group, to cheer for their favorite sports team.1 Identifying with a tribe is a very strong emotional force. People will die for it. And once you get people to identify with a tribe, the beliefs which are the attire of that tribe will be spoken with the full passion of belonging to that tribe.
1 This is the foundation on which rests the swindle of “Republicans vs. Democrats” and analogous false dilemmas in other countries, but that’s a topic for another time.
Eliezer, I have thought of another sort of belief that is not an anticipation-controller. Sometimes, I hear quite smart young people (who don't just wear beliefs as attire) profess to a belief in physicalism about qualia, or in libertarianism, or in the virtues of the scientific method, or in anti-pseudoscience (a la Martin Gardner), or in global-warming skepticism (a la Bjorn Lomborg), or in consequentialist egoism, or some similar broad philosophical or political doctrine. When I talk to these people, I find out that they can give a number of good arguments for why someone should follow their position, but that they have little to say in response to arguments for why people should follow alternative positions. For example, they might be able to clearly state various arguments for libertarianism, and to respond well to counters to those arguments. Yet when I tell them various arguments in favor of alternative positions (e.g. democratic socialism), their attempted rebuttals are much weaker in quality than their positive arguments for the position they claim to hold.
This usually occurs because these people have read good books or articles advocating physicalism, libertarianism, and egoism, and have learned (and been convinced by) the arguments contained therein. After reading these books, these people want to talk to others about what they've read and show that they can understand and reconstruct difficult arguments. They could just say to their acquaintances something like "I've read this book and I'd like to discuss some of the arguments in it with you". But, for various reasons, they often instigate such conversations by saying: "I don't think there should be any income tax at all. nor any other taxes. I'm a libertarian." From here, a heated discussion may ensue about the merits of libertarianism, in which the neophyte can relate all his carefully reconstructed arguments to his audience. This allows the new libertarian to look clever (since he can relate good arguments) and well-read (since he can quote Nozick's views on politics). It also provides the libertarian with practice in thinking and arguing on the spot, and in articulating difficult ideas.
I don't count this as belief as anticipation-controller. [I'll leave aside questions about whether beliefs in political or ethical doctrines can have empirically testable consequences. The point I'm making works just as well with global-warming skepticism as it does with libertarianism or dualism.] The person who calls himself a libertarian or a global warming skeptic after reading a couple of books and a few articles arguing for libertarianism or global-warming skepticism will often acknowledge (if honest) that if he'd started by reading books advocating alternative views, then he would not have come to be a libertarian or global-warming skeptic. He knows that he hasn't made an attempt to hear views from both sides of contentious issues, despite their being very smart and thoughtful people advocating opposing.
Yet this lack of balance in his reading is not a problem for him. He is not actually going to act on his belief in any serious way. He's not about to give his money and time to support global-warming skepticism or libertarianism. He would probably not bet money on these doctrines being true, unless the bet was a small enough fraction of this wealth that it would be worthwhile to garner more attention. When he says "I'm a libertarian", what he means is "I can articulate a number of good arguments for libertarianism, along with replies to common objections to these arguments".
I think that some professional philosophers hold beliefs in a similar way. The philosopher might come up with some clever arguments for position X. Instead of writing up a paper or blog post that simply relates these clever arguments, he will probably write an article or book that gives lots of arguments for position X, including his new clever arguments (e.g. on anti-dualism). In spending lots of time studying all the good arguments for X (and in refining his own clever arguments), he will end up with an impressive ability to make arguments in support of X. Yet he probably won't have given the same open-minded and lengthy study to arguments in support of alternatives to X (i.e. not-X). Hence, when he says to people that he is an Xist or that he believes in X, what he means is "I can give lots of really sophisticated arguments for X".
(This is not true of all philosophers, as some seem to strive to criticize their own positions. Also, it is not just philosophers that are guilty of this. Some scientists will spend their lives doing experiments that provide evidence for some view X, and they won't have invested as much time in learning about the experiments and arguments of people who have been trying to show that not-X.)