cross-posted on the EA Forum
I'm interested in questions of the form, "I have a bit of metadata/structure to the question, but I know very little about the content of the question (or alternatively, I'm too worried about biases/hacks to how I think about the problem or what pieces of information to pay attention to). In those situations, what prior should I start with?"
I'm not sure if there is a more technical term than "low-information prior."
Some examples of what I found useful recently:
1. Laplace's Rule of Succession, for when the underlying mechanism is unknown.
2. Percentage of binary questions that resolves as "yes" on Metaculus. It turns out that of all binary (Yes-No) questions asked on the prediction platform Metaculus, 29% of them resolved yes. This means that even if you know nothing about the content of a Metaculus question, a reasonable starting point for answering a randomly selected binary Metaculus question is 29%.
In both cases, obviously there are reasons to override the prior (for example, you can arbitrarily flip all questions on Metaculus such that your prior is now 71%). However (I claim), having a decent prior is nonetheless useful in practice, even if it's theoretically unprincipled.
I'd be interested in seeing something like 5-10 examples of low-information priors as useful as the rule of succession or the Metaculus binary prior.
The Lindy Effect gives no insight about which of the two books will be more “relevant“. For example, you could be comparing two political biographies, one on Donald Trump and the other on Jimmy Carter. They might both look equally interesting, but the Trump biography will make you look better informed about current affairs.
Choosing the timely rather than the timeless book is a valid rule. There‘ll always be time for the timeless literature later but the timely literature gives you the most bang for your buck if you read it now.
The Lindy Effect only tells you which of the two books is more likely to remain in print for another 40 years. It doesn’t even give you insight on how many total copies will be sold of each book. Maybe one will sell a million copies this year, 1,000 the next, and be out of print in two years. The other will sell a steady 10,000 copies per year for 40 years. The first one still will outsell it over that period of time.
What I find frustrating about the Lindy Effect, and other low-info priors like Chesterton’s Fence, is the way they get spun into heuristics for conservatism by conflating the precise claim they make with other claims that feel related but really aren’t.