Thinking, Fast and Slow: A Review

Learning how we think can be a powerful tool for thinking better.

July 11, 2017Filed under Blog#book-reviews#booksMarkdown source

I keep my book review ratings simple—they’re either required, recommended, recommended with qualifications, or not recommended. If you want the TL;DR, this is it:

Recommended: Kahneman is a talented writer, has a fascinating research history, and makes a good case; there’s a lot to learn here, and the quibbles I have are just that: quibbles.


I’ve heard very good things about Daniel Kahneman’s Thinking, Fast and Slow, so when friends asked what they might get me for my birthday, it came to mind quickly. I didn’t spend long second-guessing the choice, and it’s not one I’ve regretted in the least (even though I have my differences with the book). That experience—an immediate choice, based on some degree of prior knowledge (but not that much); followed by basic continuation along the same judgment without giving it much further thought—is itself representative of many of the themes of the book. How do we choose? What makes us decide the things we do, and why? How can we make better decisions? Why do we so often make irrational choices, and so quickly, over and against what we might choose if we slowed down to think through our decisions?

Thinking, Fast and Slow takes up all of those questions and runs with them. Kahneman, a Nobel Prize winner in economics but himself a psychologist by training and decades of practice, produced here a popularization of decades of research on how people think. His basic thesis is that we have two systems of thought: One is quick to the point of immediacy and even functioning unconsciously, intuitionist or heuristic in nature, and extremely effective and reliable for many situations—but because it is intuitionist or heuristic, also biased in certain predictable ways. The other is much slower, but capable of careful and rational consideration, not prone to the same kinds of mistakes as the first but also substantially more work to engage and itself readily enough misled by the judgments we make with that first system of thinking.

In the first quarter or so of the book, Kahneman makes his case that these two systems actually do characterize human thought, at least in broad strokes. And it’s a good case that he makes. Many of the examples he cites I was readily enough able to see playing out in my own mind, whether in real-time or by reflecting on past decision-making and judgment-making instances. This is also the part of the book on the strongest research ground, from what I can tell as an outsider. On the whole, I came away convinced of that basic theme. Whatever other places I differ with him, and there are a few, I do recommend the book for its first quarter at a minimum.

The latter parts of the book shift into examinations of specific ways that those two systems-of-thinking actually play out in practice, and here the material, though still strong overall, was a great deal more arguable. Much of this draws heavily on studies in psychology—and some of those studies have since run into some really serious problems with reproducibility. So much so that Kahneman—himself a popularizer rather than a producer of those specific experiments—wrote an open letter to the community of researchers asking them to do the hard work of either reproducing their results or walking back their claims.1 As such, even if I agreed with Kahneman philosophically throughout (and I don’t; more on that in a moment), there would be some gaps in the final section of the book.

Beyond some of these kinds of overall weaknesses, there’s also a downside to the rhetorical approach Kahneman takes. Throughout, he adopts an extremely conversational style, addressing the reader quite directly. As such, many of his claims take the form “You did something when you encountered some test in the text.” Many of these work and prove accurate… but quite a few of them don’t, too. The specifics will differ for everyone, of course, based on how well-trained they are at certain kinds of reasoning, their backgrounds, their ethical systems, and the like. But it happens, and it happened to me fairly often during the course of reading the book. One of the most striking examples was near the end, where Kahneman was trying to show that we often will assign different values to given things when evaluated independently than when evaluated side-by-side. He made there a claim about what the reader did or didn’t do in evaluating the needs of humans vs. evaluating the need for dolphins—specifically, that the specific valuation of humans over dolphins didn’t emerge until the two were compared more directly. But it did for me; it was the first thought I had. I’ll grant his broader point, of course, and I don’t doubt that in many cases the studies he cites represent real tendencies. I can certainly think of other scenarios where a similar kind of comparison might break down. But it’s an interesting place where the conversational style breaks down: you can only assert so much and get away with it. On the other hand, a book full of questions of the “Did you think something?” sort would get old quickly. This is a hard line to walk, and on the whole I think the style worked—but it had that nagging weakness, which stuck out to me fairly frequently when reading the book.

I also found, unsurprisingly, that Kahneman and I differ fairly strongly in our view of both ethics and human nature. On the whole, this didn’t directly impact my appreciation of the book. On occasion, however, his view of human nature diverged quite sharply from the Christian view. In particular, he left little room for the idea of our nature being designed to have certain kinds of limitations about it and majored heavily on rationalism as ideal. I don’t think strict rationalism is in fact ideal, and whereas he contents himself with describing Econs as an incomplete view of how humans work (but one that he often refers to in rather aspirational ways), I would go much further: it would in fact be wrong for humans to act as the purely “rational” agents of much standard economic theory, because that kind of rationalism is in fact merely a particular brand of utilitarianism. I’d go further still and say that utilitarianism is itself a kind of irrationality, and that one of the ways human nature continues to function as a divine image is in our deep-seated and nearly inescapable distinguishing between kinds of things that economists tell us are of equal utility: for so they may be, but there is more to God’s green earth than the uses to which we may put it.

But important though those differences are, they are also far afield of the thesis and even the majority emphasis of the book. Indeed, precisely because it does acknowledge so clearly the way humans actually work, the book can serve as a helpful entry-point for conversation about the limits of utilitarianism. If utility is not a perfect description of how humans do work, perhaps it also behooves us to consider if it’s a good description of how we ought to work.

More than that, the book as a whole is a genuinely good and insightful volume. Many of the kinds of biases and errors Kahneman point out are unarguably problems—and many of them contribute significantly to systematic issues in the world at large. Being more aware of how our ability to think clearly and rightly degrades when we are, say, tired and hungry, should make us think carefully about assigning a judge a long docket of cases to sentence: why should two men who committed the same crime get different punishments simply because one received his sentence in the morning when the judge was alert and fresh off her breakfast and coffee, and the other late in the morning when she was feeling hungry and drained? There are not easy solutions to these kinds of problems, but we cannot even begin to address them unless we know they exist in the first place. Similarly, at a personal level, knowing these things about ourselves can help us be aware of where we’re vulnerable to them and adjust accordingly—whether by aiming to increase our awareness of them situation-by-situation, or (better) by making careful choices when able to do so which we can then lean on in the situations where we have to make snap judgments.

There’s a lot more to say about that latter point, not least on the topic of Christian formation, discipleship, and catechesis. But that’s for another post. Read at least the first section of Thinking, Fast and Slow: you’ll profit from it, and you’ll enjoy it.


  1. Hat tip to Sarah Constantin for bringing that letter to my attention. Her blog is well worth your time in general: you’ll learn from her even when you disagree with her, as I often do.)