I'd heard rumors that some leading Bayesians had achieved rank in the Bardic Conspiracy. But I wasn't aware that every two years, some of the world's top statisticians hold a Bayesian Cabaret, full of songs, dances, and skits about Bayesian probability theory.

...no, really. Really. I think my favorite has got to be this one.

YouTube seems to be full of this stuff, including What A Bayesian World and We Didn't Start The Prior. Be sure to also check out some of the recordings and the Bayesian Songbook.

Eliezer's finished his sequences, and it's a new era for Less Wrong. Let's celebrate...Bayesian style!

Related to: The Psychological Unity of Humankind, Instrumental vs. Epistemic: A Bardic Perspective

"Everyone generalizes from one example. At least, I do."

   -- Vlad Taltos (Issola, Steven Brust)

My old professor, David Berman, liked to talk about what he called the "typical mind fallacy", which he illustrated through the following example:

There was a debate, in the late 1800s, about whether "imagination" was simply a turn of phrase or a real phenomenon. That is, can people actually create images in their minds which they see vividly, or do they simply say "I saw it in my mind" as a metaphor for considering what it looked like?

Upon hearing this, my response was "How the stars was this actually a real debate? Of course we have mental imagery. Anyone who doesn't think we have mental imagery is either such a fanatical Behaviorist that she doubts the evidence of her own senses, or simply insane." Unfortunately, the professor was able to parade a long list of famous people who denied mental imagery, including some leading scientists of the era. And this was all before Behaviorism even existed.

The debate was resolved by Francis Galton, a fascinating man who among other achievements invented eugenics, the "wisdom of crowds", and standard deviation. Galton gave people some very detailed surveys, and found that some people did have mental imagery and others didn't. The ones who did had simply assumed everyone did, and the ones who didn't had simply assumed everyone didn't, to the point of coming up with absurd justifications for why they were lying or misunderstanding the question. There was a wide spectrum of imaging ability, from about five percent of people with perfect eidetic imagery¹ to three percent of people completely unable to form mental images².

Dr. Berman dubbed this the Typical Mind Fallacy: the human tendency to believe that one's own mental structure can be generalized to apply to everyone else's.

Sunlight enriched air already alive with curiosity, as dawn rose on Brennan and his fellow students in the place to which Jeffreyssai had summoned them.

They sat there and waited, the five, at the top of the great glassy crag that was sometimes called Mount Mirror, and more often simply left unnamed.  The high top and peak of the mountain, from which you could see all the lands below and seas beyond.

(Well, not all the lands below, nor seas beyond.  So far as anyone knew, there was no place in the world from which all the world was visible; nor, equivalently, any kind of vision that would see through all obstacle-horizons.  In the end it was the top only of one particular mountain: there were other peaks, and from their tops you would see other lands below; even though, in the end, it was all a single world.)

"What do you think comes next?" said Hiriwa.  Her eyes were bright, and she gazed to the far horizons like a lord.

Taji shrugged, though his own eyes were alive with anticipation.  "Jeffreyssai's last lesson doesn't have any obvious sequel that I can think of.  In fact, I think we've learned just about everything that I knew the beisutsukai masters know.  What's left, then -"

"Are the real secrets," Yin completed the thought.

Hiriwa and Taji and Yin shared a grin, among themselves.

Styrlyn wasn't smiling.  Brennan suspected rather strongly that Styrlyn was older than he had admitted.

Brennan wasn't smiling either.  He might be young, but he kept high company, and had witnesssed some of what went on behind the curtains of the world.  Secrets had their price, always, that was the barrier that made them secrets; and Brennan thought he had a good idea of what this price might be.

Previously in series:  Well-Kept Gardens Die By Pacifism
Followup to:  My Way

I have said a thing or two about rationality, these past months.  I have said a thing or two about how to untangle questions that have become confused, and how to tell the difference between real reasoning and fake reasoning, and the will to become stronger that leads you to try before you flee; I have said something about doing the impossible.

And these are all techniques that I developed in the course of my own projects—which is why there is so much about cognitive reductionism, say—and it is possible that your mileage may vary in trying to apply it yourself.  The one's mileage may vary.  Still, those wandering about asking "But what good is it?" might consider rereading some of the earlier posts; knowing about e.g. the conjunction fallacy and how to spot it in an argument, hardly seems esoteric.  Understanding why motivated skepticism is bad for you can constitute the whole difference, I suspect, between a smart person who ends up smart and a smart person who ends up stupid.  Affective death spirals consume many among the unwary...

Yet there is, I think, more absent than present in this "art of rationality"—defeating akrasia and coordinating groups are two of the deficits I feel most keenly.  I've concentrated more heavily on epistemic rationality than instrumental rationality, in general.  And then there's training, teaching, verification, and becoming a proper experimental science based on that.  And if you generalize a bit further, then building the Art could also be taken to include issues like developing better introductory literature, developing better slogans for public relations, establishing common cause with other Enlightenment subtasks, analyzing and addressing the gender imbalance problem...

But those small pieces of rationality that I've set out... I hope... just maybe...

I suspect—you could even call it a guess—that there is a barrier to getting started, in this matter of rationality.  Where by default, in the beginning, you don't have enough to build on.  Indeed so little that you don't have a clue that more exists, that there is an Art to be found.  And if you do begin to sense that more is possible—then you may just instantaneously go wrong.  As David Stove observes—I'm not going to link it, because it deserves its own post—most "great thinkers" in philosophy, e.g. Hegel, are properly objects of pity.  That's what happens by default to anyone who sets out to develop the art of thinking; they develop fake answers.

So you think you want to be rational, to believe what is true even when sirens tempt you?  Great, get to work; there's lots you can do.  Do you want to justifiably believe that you are more rational than others, smugly knowing your beliefs are more accurate?  Hold on; this is hard. 

Humans nearly universally find excuses to believe that they are more correct that others, at least on the important things. They point to others' incredible beliefs, to biases afflicting others, and to estimation tasks where they are especially skilled.  But they forget most everyone can point to such things.  

But shouldn't you get more rationality credit if you spend more time studying common biases, statistical techniques, and the like?  Well this would be good evidence of your rationality if you were in fact pretty rational about your rationality, i.e., if you knew that when you read or discussed such issues your mind would then systematically, broadly, and reasonably incorporate those insights into your reasoning processes. 

But what if your mind is far from rational?  What if your mind is likely to just go through the motions of studying rationality to allow itself to smugly believe it is more accurate, or to bond you more closely to your social allies? 

It seems to me that if you are serious about actually being rational, rather than just believing in your rationality or joining a group that thinks itself rational, you should try hard and often to test your rationality.  But how can you do that? 

To test the rationality of your beliefs, you could sometimes declare beliefs, and later score those beliefs via tests where high scoring beliefs tend to be more rational.  Better tests are those where scores are more tightly and reliably correlated with rationality.  So, what are good rationality tests?