Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: "Rationalist Discourse" Is Like "Physicist Motors", published by Zack M Davis on February 26, 2023 on LessWrong.

Imagine being a student of physics, and coming across a blog post proposing a list of guidelines for "physicist motors"—motor designs informed by the knowledge of physicists, unlike ordinary motors.

Even if most of the things on the list seemed like sensible advice to keep in mind when designing a motor, the framing would seem very odd. The laws of physics describe how energy can be converted into work. To the extent that any motor accomplishes anything, it happens within the laws of physics. There are theoretical ideals describing how motors need to work in principle, like the Carnot engine, but you can't actually build an ideal Carnot engine; real-world electric motors or diesel motors or jet engines all have their own idiosyncratic lore depending on the application and the materials at hand; an engineer who worked on one, might not the be best person to work on another. You might appeal to principles of physics to explain why some particular motor is inefficient or poorly-designed, but you would not speak of physicist motors as if that were a distinct category of thing—and if someone did, you might quietly begin to doubt how much they really knew about physics.

As a student of rationality, I feel the same way about guidelines for "rationalist discourse." The laws of probability and decision theory describe how information can be converted into optimization power. To the extent that any discourse accomplishes anything, it happens within the laws of rationality.

Rob Bensinger proposes "Elements of Rationalist Discourse" as a companion to Duncan Sabien's earlier "Basics of Rationalist Discourse". Most of the things on both lists are, indeed, sensible advice that one might do well to keep in mind when arguing with people, but as Bensinger notes, "Probably this new version also won't match 'the basics' as other people perceive them."

But there's a reason for that: a list of guidelines has the wrong type signature for being "the basics". The actual basics are the principles of rationality one would appeal to explain which guidelines are a good idea: principles like how evidence is the systematic correlation between possible states of your observations and possible states of reality, how you need evidence to locate the correct hypothesis in the space of possibilities, how the quality of your conclusion can only be improved by arguments that have the power to change that conclusion.

Contemplating these basics, it should be clear that there's just not going to be anything like a unique style of "rationalist discourse", any more than there is a unique "physicist motor." There are theoretical ideals describing how discourse needs to work in principle, like Bayesian reasoners with common priors exchanging probability estimates, but you can't actually build an ideal Bayesian reasoner. Rather, different discourse algorithms (the collective analogue of "cognitive algorithm") leverage the laws of rationality to convert information into optimization in somewhat different ways, depending on the application and the population of interlocutors at hand, much as electric motors and jet engines both leverage the laws of physics to convert energy into work without being identical to each other, and with each requiring their own engineering sub-specialty to design.

Or to use another classic metaphor, there's also just not going to be a unique martial art. Boxing and karate and ju-jitsu all have their own idiosyncratic lore adapted to different combat circumstances, and a master of one would easily defeat a novice of the other. One might appeal to the laws of physics and the properties of the human body to explain why some particular martial arts school was not teaching their st...