Textbook Rationality:
Rationality – and why we should teach it in schools

Ivan Phillips, Barley Lane Books (January 29, 2021)

A while back I tried to articulate some embryonic thoughts about how we need to really dig in and figure out how to raise an alarm that culturally we are running low on critical thinking. Then not long after, an ad for the book above showed up in my feed, and caught my attention. This guy is way ahead of me! I snapped up the book and really enjoyed it.

My purpose today is to try to do it justice in a book review.

To be clear, I have not previously spoken with the author nor do I have a financial incentive to write this review. I’m just a human interested in bringing rational thinking to the center stage of our culture.

Another disclaimer is that I am not well-read in this particular literature. My understanding is that (of course) many of the ideas discussed are very old. But a concise and effective exposition is hard to find, and I think the book has both qualities. Old knowledge that’s buried in larger works is not as useful. Even if all the ideas already appear elsewhere in the literature, the fresh exposition still gives this work immense value.

What is the book about? What’s in it?

The book discusses what rational thinking is (and what it is not.) The closest thing to it taught in the present day education (U.S. at least) is so-called “critical thinking,” which helps students to evaluate the quality of arguments, often touching on logic, logical fallacies, and perhaps even cognitive biases. These are important, but the book makes a compelling argument that something is missing, leaving the curriculum unfocused and not well-understood.

What is neglected (the book says) is the rationale for extracting knowledge from information, and the way we gain confidence in what we think is true (epistemology). Students don’t really learn what deductive and inductive reasoning are, or how they work with each other, either.

The author covers Bayesian epistemology as the best candidate for a standard we can use for rational thought. That’s when things start sounding like the scientific method, and for good reason: the scientific community is already applying Bayesian epistemology with great success.

Chapter 1 outlines the general program of the book. It discusses what “ideal rationality” is, facts versus values, and discusses how this could be used as a high school course.

Chapter 2 introduces the fundamentals of rational thinking, including what valid and sound arguments are, what consistency and contradiction are, and what exactly inferential and deductive reasoning mean. It’s not just a list of definitions: you will definitely see how they interlock and are indispensable for what follows.

Bayesian reasoning is where the math comes in (Chapter 3), but don’t worry. A fair portion of the book is concerned with a gentle introduction to how Bayesian reasoning works. If you are already somewhat familiar with it, you will have a new appreciation for its importance, and if you are unfamiliar with it I think you will have no problem with the exposition. It is well worth working through it. After that, the author walks through several illustrations of how Bayesian reasoning is applied (Chapter 4).

Chapter 5 goes broad, giving general advice and leaving pointers to more specialized works on very important topics. Among the topics mentioned these are some of my favorites: separating fact from opinion, what it means when a new study contradicts and older one, and defending yourself against misinformation.

What is not in the book?

The book is well-written and self-contained. There are several points which are delegated out to other popular books which handle sub-topics well (for example, specific cognitive biases are not treated in this book, but ample references are given instead.). This does not detract from the book, and keeps it lightweight and modular.

It is very difficult to find anything to disagree with in the book, but there is this: the very first line in the introduction is

Rationality is something we all desire.

Sadly, I think this is less true than the author intended. Everyone proactively opting to read this book probably does agree with the statement, but the real heart of the problem we’re facing today is that there are people who are indifferent about rational thinking or, even worse, who treat it with contempt, at least in some circumstances.

How do we get through to the rest? It would be a shame for this book to be trapped inside the bubble of people who are already inclined to rational thinking, because the people who most need it are outside the bubble. I don’t think the book mentions anything substantial about this, and I was really hoping for some general advice about broaching the subject to potentially resistant parties, or at least pointers to works that do give such advice.

Another topic related to this that I was hoping to have a word on is how radicalization works, and how we might mitigate it. Radicalization may be the wrong word. What I mean to refer to are extreme partisans, those who have adopted a certain position and are convinced they have nothing further to learn from alternative viewpoints, and therefore do not consider evidence rationally, but instead process it with group-think.

Both topics would make a great additions to the advice and reference lineup in Chapter 5.

But that said, if you consider the book as a sort of field manual for teaching a high school level student (or younger) it is less likely they will be resistant or radicalized.

Finally, I have one comment about the coverage of conspiracy theories. Most of the discussion about conspiracies is about how the culture of the scientific community makes conspiracy highly improbable to execute, and how people lean on the notion of conspiracy to prop up their position when the evidence does not support (or no evidence exists for) their position.

This is all very helpful in knowing when a conspiracy-related argument can be discarded.

But then this went off like a grenade late in the book:

The only organizations that can pull off mass conspiracies are industry trade groups and intelligence agencies.

Chapter 5, Rational Judgement Questionnaire

At this point one wonders what examples of actual mass conspiracies are. What do they look like, what are their hallmarks, and what eventually gave them away? Yes, we’ll probably be able to dismiss accusations of conspiracy most of the time, but we could do so much more confidently by understanding what true conspiracies look like. This would also make a great addition to Chapter 5.

Should you read the book?

Absolutely. Here are other practical qualities that might win you over:

  • Everyone needs the information inside it.
  • It’s not too simple and it’s not too hard.
  • It is not expensive.
  • It is not too long.
  • It has practical advice.

Why I feel the issue is important

If the role of rationality is proper interpretation of information, then there are several reasons we need to be better at it collectively, as a species.

Firstly is that we are being overwhelmed by a firehose of information, and we need to be better at systematically processing it in an objective way. When we find our brains redlining because of the load of information placed on them, it is all too easy to fall back on the system that relies on intuition and instinct to process things, since it is faster. But as we know, this will inevitably risk irrational decisions.

I don’t think it will be possible to be fully rational at the same speed as intuition, but at least we must be on the lookout for situations which demand the full use of rational reasoning, so that we can resist processing them expediently with intuition alone. And who knows, maybe with enough exercise one can develop good “rational reflexes” that are maybe not fully rational but which are better than the crude instinctive ones.

Secondly, as advances in science progress and we learn more and more about the brain, and as information manipulators out there gather experience, our weaknesses in our psychology are more and more likely to be exploited. A well-trained habit of rationality might not completely guard against such attacks, but it will certainly be and important part of the defense.


In Textbook Rationality, the author establishes a proposed notion of rationality, distinguishes it from traditional critical thinking, explains what has been not been emphasized enough, and argues that we can provide a well-rounded rationality education by adding to the discussion of critical thinking. Much practical advice and excellent references to other work spring up along the way. I very much recommend reading this book.

If you like, you can check out the author’s website: https://rationalfuture.org/wp/