like logic? "An Intuitive Explanation of Bayesian Reasoning"

[Darren Dirt]

http://yudkowsky.net/bayes/bayes.html

Neato but challenging math, but Eliezer Yudkowsky's hilarious writing style makes it worth skimming through at the very least...

Your friends and colleagues are talking about something called "Bayes' Theorem" or "Bayes' Rule", or something called Bayesian reasoning.  They sound really enthusiastic about it, too, so you google and find a webpage about Bayes' Theorem and...

It's this equation.  That's all.  Just one equation.  The page you found gives a definition of it, but it doesn't say what it is, or why it's useful, or why your friends would be interested in it.  It looks like this random statistics thing.

So you came here.  Maybe you don't understand what the equation says.  Maybe you understand it in theory, but every time you try to apply it in practice you get mixed up trying to remember the difference between p(a|x) and p(x|a), and whether p(a)*p(x|a) belongs in the numerator or the denominator.  Maybe you see the theorem, and you understand the theorem, and you can use the theorem, but you can't understand why your friends and/or research colleagues seem to think it's the secret of the universe.  Maybe your friends are all wearing Bayes' Theorem T-shirts, and you're feeling left out.  Maybe you're a girl looking for a boyfriend, but the boy you're interested in refuses to date anyone who "isn't Bayesian".  What matters is that Bayes is cool, and if you don't know Bayes, you aren't cool.



Q.  What is the Bayesian Conspiracy?
A.  The Bayesian Conspiracy is a multinational, interdisciplinary, and shadowy group of scientists that controls publication, grants, tenure, and the illicit traffic in grad students.  The best way to be accepted into the Bayesian Conspiracy is to join the Campus Crusade for Bayes in high school or college, and gradually work your way up to the inner circles.  It is rumored that at the upper levels of the Bayesian Conspiracy exist nine silent figures known only as the Bayes Council.


Q.  Are there any limits to the power of Bayes' Theorem?
A.  According to legend, one who fully grasped Bayes' Theorem would gain the ability to create and physically enter an alternate universe using only off-the-shelf equipment and a short computer program.  One who fully grasps Bayes' Theorem, yet remains in our universe to aid others, is known as a Bayesattva.

...And that's Bayes' Theorem.  Rational inference on the left end, physical causality on the right end; an equation with mind on one side and reality on the other.  Remember how the scientific method turned out to be a special case of Bayes' Theorem?  If you wanted to put it poetically, you could say that Bayes' Theorem binds reasoning into the physical universe.
Okay, we're done.


If you liked An Intuitive Explanation of Bayesian Reasoning, you may also wish to read A Technical Explanation of Technical Explanation (http://yudkowsky.net/bayes/technical.html) by the same author, which goes into greater detail on the application of Bayescraft to human rationality and the philosophy of science. You may also enjoy the Twelve Virtues of Rationality (http://yudkowsky.net/virtues/) and The Simple Truth (http://sl4.org/wiki/TheSimpleTruth).

My brain hurts. But I like it.

[Lazybones]

All I think about when I here Bayesian is how great it was for about 6 months until SPAMers started padding messages with random quotes from the internet to get past filtering.

[Adams]

Most of the Bayesian filters need constant data to learn from. Which makes it a constant pain in the ass to manage.