Part One: Taking rationalism seriously

In the Cells of the Eggplant aims to level up rationality. As a first step, we need to understand how and when and why rationality works. Rationalism is a theory about that. “Taking it seriously” implies investigating whether the theory is correct. We’ll find it isn’t.

We need a better understanding of rationality. Fortunately, one is available, and Part Three of The Eggplant explains it. So why not just start there?

Rationalism is the familiar, taken-for-granted understanding of rationality, accepted without much thought by most technical professionals. You learned it—largely by osmosis—in high school science classes. It’s simple and it makes sense. It’s a good-enough explanation of how you solved assigned coursework problems as an undergraduate. It’s uncommon to notice it’s not a good description of your experience of using rationality on the job, in the real world, after leaving school.

The Eggplant’s explanation of rationality is quite different, not just in content, but in “feel.” It relies on concepts you may not have encountered before, and that may seem strange or even repellent at first. If you jumped straight into Part Three, you might find its explanations alien, implausible, and complex in comparison with rationalism. The natural reaction: “this is weird nonsense; why not just rationalism?”

“Why not just rationalism” is half the agenda of Part One. Until one accepts that rationalism faces serious unresolved problems, not just as a philosophical theory but as a guide to practice, it’s difficult to take any alternative seriously.

Happily, it turns out that the specific ways rationalism is wrong point straight at a better understanding. That’s the other half of the agenda: causal diagnosis of rationalism’s many failure modes. That guides the construction of the alternative.

A pattern emerges: the overall reason rationalism can’t work. Every rationalist theory gets wrecked, in stormy seas of counterexamples, on the black reef of nebulosity.

This implies that the relationship between crisp rational systems and nebulous reality is key to understanding how and when and why rationality works. That leads naturally to the quite different understanding in Part Three.

The structure of Part One

The first three chapters of Part One are preliminary. They provide definitions of the subject matter, and introduce needed concepts. They also explain what sort of explanation The Eggplant aims for. It is not cognitive science, philosophy, or history. It is practical, not theoretical—although it often has to address theories, to dispel misconceptions that are misleading for practice.

Most of Part One works through a series of increasingly sophisticated, standard rationalist models that try to explain what it means to believe a true fact. That is a fundamental question for rationalism.

The aim here is not to conclusively refute these theories—because it is uncontroversial that each does fail. Rather, we will examine each in enough detail to find its root problem. Then it becomes plausible that no similar model can work. That suggests we need some quite different story.

Part One poses a potential danger. For many skilled in the use of technical rationality, rationalism is an important part of personal identity. Coming to understand how it is mistaken and sometimes harmful can be emotionally devastating. “Bypassing post-rationalist nihilism,” at the end of Part One, explains how to avoid that shock. If the first twinges of doubt in rationalism induce vertigo, it may be good to skip ahead to read that.