[This post was primarily written in 2015, after I gave a related talk, and other bits in 2018; I decided to finish writing it now because of a recent SSC post.]

The standard forms of divination that I’ve seen in contemporary Western culture--astrology, fortune cookies, lotteries, that sort of thing--seem pretty worthless to me. They’re like trying to extract information from a random number generator, which is a generally hopeless phenomenon because of conservation of expected evidence. Thus I had mostly written off divination; although I've come across some arguments that divination served as a way to implement mixed strategies in competitive games. (Hunters would decide where to hunt by burning bones, which generated an approximately random map of their location, preventing their targets from learning where the humans liked to hunt and avoiding that location.^[1]) But then I came across this striking passage, and sat up straight:

One performs the rain sacrifice and it rains. Why? I say: there is no special reason why. It is the same as when one does not perform the rain sacrifice and it rains anyway. When the sun and moon suffer eclipse, one tries to save them. When Heaven sends drought, one performs the rain sacrifice. One performs divination and only then decides on important affairs. But this is not to be regarded as bringing one what one seeks, but rather is done to give things proper form. Thus, the gentleman regards this as proper form, but the common people regard it as connecting with spirits. If one regards it as proper form, one will have good fortune. If one regards it as connecting with spirits, one will have misfortune.

This is from Eric L. Hutton's translation of a collection of essays called Xunzi (presumably written by Xunzi, an ancient Chinese philosopher who was Confucian with heavy Legalist influences). The book was overall remarkable in how much of Xunzi's brilliance shone through, which is something I very rarely think about authors. (Talking to another rationalist who was more familiar with Chinese philosophy than I was, he also had this impression that Xunzi simply had a lot more mental horsepower than many other core figures.) By the end of it, I was asking myself, "if they had this much of rationality figured out back then, why didn't they conquer the world?" Then I looked into the history a bit more and figured out that two of Xunzi's students were core figures in Qin Shi Huang's unification of China to become the First Emperor.

So this paragraph stuck with me. When Xunzi talks about the way that earlier kings did things, I registered it as an applause light and moved on. When he talked about how an important role of government was to prevent innovation in music, I registered it as covering a very different thing than what I think of when I think about 'music' and moved on. But when he specifically called out the reason why I (and most educated people I know) don't pay much attention to astrology or other sorts of divination or magic, said "yeah, those would be dumb reasons to do this," and then said "but there's still a reason", I was curious. What's the proper form that he's talking about? (Sadly, this was left as an exercise for the reader; the surrounding paragraphs are only vaguely related.)

In his introduction, Hutton summarizes the relevant portion of Xunzi's philosophy:

In this process of becoming good, ritual plays an especially important role in Xunzi's view. As he conceives them, the rituals constitute a set of standards for proper behavior that were created by the past sages and should govern virtually every aspect of a person's life. These rituals are not inviolable rules: Xunzi allows that people with developed moral judgment may need to depart from the strict dictates of ritual on some occasions, but he thinks those just beginning the process of moral learning need to submit completely to the requirements of ritual. Of the many important roles played by the rituals in making people good on Xunzi's view, three particularly deserve mention here. First the rituals serve to display certain attitudes and emotions. The ritually prescribed actions in the case of mourning, for instance, exhibit grief over the loss of a loved one, whether or not the ritual practitioner actually feels sadness. Second, even if the ritual practitioner does not actually feel the particular attitude or emotion embodied in the ritual, Xunzi believes that repeated performance of the ritual can, when done properly, serve to cultivate those attitudes and emotions in the person. To use a modern example, toddlers who do not know to be grateful when given a gift may be taught to say "thank you" and may do so without any understanding of its meaning or a feeling or gratitude. With repetition, time, and a more mature understanding of the meaning of the phrase, many of these children grow into adults who not only feel gratitude upon receiving gifts but also say "thank you" as a conscious expression of that feeling. Similarly, on Xunzi's view, rituals serve to inculcate attitudes and feelings, such as caring and respect, that are characteristic of virtue, and then serve to express a person's virtue once it is fully developed. A third important function of the rituals is to allot different responsibilities, privileges, and goods to different individuals, and thereby help to prevent conflict over those things among people.

So what is cultivated by performing divination?

The first step is figuring out what sort of divination we're discussing. Xunzi probably had in mind the I Ching, a book with 64 sections, each corresponding to a situation or perspective, and advice appropriate for that situation. In the simplest version, one generates six random bits and then consults the appropriate chapter. I actually tried this for about a month, and then have done it off and on since then. I noticed several things about it that seemed useful:

Entries in the I Ching typically focused on perspectives or principles instead of situations, consequences, or actions. Today’s Taurus horoscope says “your self-esteem might be challenged by a fast talker or unpleasant situation” and counsels me “don’t accept things as they appear on first glance,” whereas the I Ching reading I just randomly selected talks about how following proper principles leads to increased power and how the increased power tempts us to abandon the principles that generated that power. This makes it much easier to scan one’s life and see where the perspectives shed new light on a situation, or where principles had been ignored. (One of the early successes of my I Ching practice was a chapter that suggested reaching out to a trusted guide for advice, and I realized I should talk to a mentor at work about a developing situation, which I wouldn’t have done otherwise.)
Given that, daily divination almost filled the same role as daily retrospectives or planning sessions; I was frequently thinking about all the different parts of my life on a regular interval, using a variety of random access to filter things down.
“One performs divination and only then decides on important affairs.” Often one is faced with a challenge that is “above one’s pay grade,” and having a prescribed ritual for what sort of cognition needs to be done encourages reflection and popping out of the obvious frame. Simply thinking about a situation in the way one naturally would doesn’t correct for biases, while attempting to make sense of a situation from a randomly generated frame does help expand one’s conception of it.
Since the divination result was a particular perspective (rather than an object-level claim about events or the correct action), it was easy to see when the perspective had been ‘fully considered’ and the reflection was done. If I’m trying to make a binary choice and I flip a coin to resolve it, basically all I’m doing is checking whether or not my gut is secretly hoping the coin lands a particular way, and in cases of genuine uncertainty I will end up just as uncertain after consulting the coin flip. But when I have a situation and I resolve the questions of “what does patience have to say about X?” and “what does humility have to say about X?” then I can have the sense of having actually made progress.
It encouraged experimentation by partially decoupling one’s mood and one’s decisions. The first few days, I was instructed to consider diligence and so I worked more than I would have wanted to (and discovered that this was generally fine); on the fourth day, I joked, “when is it going to tell me to goof off and play video games?”, and then got a reading that said “effort is hopeless today; that happens, cope with it.” So despite feeling like I could have been productive, I took the day off, and later had the sense that I had confirmed my initial sense that I didn’t need to take the day off, providing data to calibrate on that I wouldn’t have gotten except through random variation.

Essentially, it looked to me like the steelman of divination is something like Oblique Strategies, where challenging situations (either ‘daily life’ or a specific important decision) are responded to by random access to a library of perspectives or approaches, and the particular claim made by a source is what distribution is most useful. There was previously an attempt on LW to learn what advice was useful, but I think on the wrong level of abstraction (the ‘do X’ variety, instead of the ‘think about X’ variety).

This approach has also served me well with other forms of divination I've since tried; a Tarot deck works by focusing your attention on a situation, and then randomly generating a frame (from an implied distribution of relevant symbols), giving one access to parts of the space that they wouldn't have considered otherwise. This also trains the habit of 'understanding alien frames'; if I am considering a conflict with another person and then have to figure out what it means that "I'm the vizier of water, the relationship is the three of earth, and the other person is strength" (where, of course, each of those is in fact an image rich in detail rather than a simple concept), this trains the habit of adopting other perspectives / figuring out how things make sense from the other point of view.

^{^}
This view is apparently contested.