Meta-rationality: An introduction

Learning to wield an invisible power

In fields requiring systematic, rational competence—science, engineering, business—some few people can do what may seem like magic.

They step into messy, complex, volatile situations and somehow transform them into routine, manageable problems. Textbook methods that were failing to come to grips with anomalies start working again.

Often these magicians have less relevant factual and conceptual knowledge than others who found the situation impossible. They may have no special skill in applying technical methods. Instead they may:

  • Notice relevant factors that others overlooked
  • Point out non-obvious gaps or friction between theory and reality
  • Ask key questions no one had thought of
  • Make new distinctions that suggest different conceptualizations of the situation
  • Change the description of the problem so that different solution approaches appear
  • Rethink the purpose of the work, and therefore technical priorities
  • Realize that difficulties others struggled with can simply be ignored, or demoted in importance
  • Apply concepts or methods from seemingly distant fields
  • Combine multiple contradictory views, not as a synthesis, but as a productive patchwork.

They produce these insights by investigating the relationship between a system of technical rationality and its context. The context includes a specific situation in which rationality is applied, the purposes for which it is used, the social dynamics of its use, and other rational systems that might also be brought to bear. This work operates not within a system of technical rationality, but around, above, and then on the system.

This is meta-rationality. This book is about that.

A slice of The Eggplant

Sliced eggplant

Image courtesy Mike

I’ve web-published a new Introduction and Part One of In the Cells of the Eggplant. Here’s why you might want to read them—or not—and how to read them if you do.

The Eggplant is—or will be—a book about meta-rationality. “Meta-rationality” means improving technical practice through reflection on the relationship between rational systems and their surrounds. You may care about meta-rationality if you want to level up your work in science, engineering, or other fields that make use of formal systems.

Is this an eggplant which I see before me?

Correspondence fairy maintaining the truth of eggplantness

Perception plays two important roles in rationalism:

  • The correspondence theory of truth does not include a causal explanation of how the correspondence between beliefs and reality comes about. Unfortunately, there are no correspondence fairies to do that job for us. Perception can do at least part of the work.

  • Rational processes of deduction and induction produce new beliefs from old ones. To get the process started, some beliefs must come from some other source. Those should be “bare facts,” which do not themselves depend on inference or interpretation. Perception is one obvious source of factual knowledge.

Acting on the truth


Dancers courtesy Jakob Owens

Rationalisms are mainly concerned with thinking correctly. However, they are often also concerned with acting, and try to provide correctness or optimality guarantees for action as well.

Rationalist theories generally take action as deriving straightforwardly from your beliefs about the current state of the world and how your actions will affect it. If those beliefs are true, then you can calculate the optimal action with some simple mathematics. Four influential theories of this sort are:

  • Game theory, in which you and an opponent alternate in choosing from a small number of possible moves whose effects are fully known, in order to achieve a defined win condition
  • Decision theory, in which you choose a single action out of a small set, which will result in one of a small number of possible outcomes, but you may have only probabilistic knowledge of the world state and the outcome of your choice
  • Control theory, in which the world is taken to be a differential equation, your beliefs are values of some real-valued variables in the equation, your actions set some variables, and you aim to maximize a function of variables
  • Means-ends planning, in which you derive a program that will bring about a well-defined goal state by taking a series of discrete actions, each of which affects the world in a well-defined way.

The math in each case is conceptually trivial. This is why epistemology is central for rationalism: the main thing is to make sure your beliefs are true. If you can do that, optimal action is guaranteed.

Statistics and the replication crisis

If probabilism were just a mistaken philosophical theory, it wouldn’t matter. Philosophy has a million silly theories.1 Most are harmless, because no one takes them seriously.2

Probabilism being wrong matters because science and engineering and education and medicine and finance and government matter to everyone’s lives, and statistical methods are widely used in all those fields. When probabilism—misplaced faith in probabilistic methods—leads you to ignore nebulosity, catastrophes result.


Probability theory may seem an attractive candidate for the foundation of rationality:

  • Whereas formal logic is rarely useful in practice, probabilistic methods are indispensable in many technical fields
  • Probability theory recognizes that absolute certainty is never possible in the eggplant-size world
  • It provides an intuitively appealing account of greater and lesser confidence in beliefs.



General explanation: Meaningness is a hypertext book. Start with an appetizer, or the table of contents. Its “metablog” includes additional essays, not part the book.

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