I started reading the book Thinking, Fast and Slow by Daniel Kahneman in early 2024. This was initially recommended to me by a friend, and I became even more motivated to read it upon hearing positive things about it from colleagues at my previous job, as many of the subtleties described in the book are extremely relevant to the appropriate design of interviews, focus groups, and surveys of human subjects in social science research. However, because it is a long book and the middle of 2024 was made busier for me by moving back to Maryland, traveling a lot, and starting a new job (some of which I have discussed in a previous post [LINK]), I could not finish reading this book until much more recently. Because of this large gap between reading the initial 60% and remaining 40% of this book, I admit that I have since forgotten many details from the initial 60% of this book. Moreover, I started making notes to myself in this post based on that initial 60% because I assumed that I would be able to finish reading the remaining 40% soon afterwards and I would therefore remember the book as a coherent whole, but because that didn't happen, many of the notes that I have made in this post that were supposed to form the skeleton of this post now no longer make as much sense to me. For these reasons, this post may seem a bit more stilted than other book review posts in this blog and will likely seem stronger/more coherent when discussing the latter 40% of the book.
The book is a lengthy exposition of novel ideas in psychology & behavioral economics that were empirically validated by the author, most often in conjunction with his longtime academic collaborator Amos Tversky. The concluding chapter does a good job of recapitulating the main ideas of the book. Most of the book explores various facets of individual & group-based human behavior based on the idea that there are effectively 2 modes through which individuals process information, which the author refers to as Systems 1 & 2. System 1 "thinks fast", making snap judgments based on limited information, heuristics, and a bit of laziness, and is the aspect of thinking that drives most day-to-day reactions & decisionmaking, while System 2 "thinks slow", making more deliberate judgments with more of an effort to gather all relevant information but must in turn be consciously engaged and ultimately disengages from mental fatigue (in favor of System 1) if engaged for too long. The book also considers how individuals' typical behaviors when faced with outcomes that are certain competing with outcomes that have known or unknown probabilities deviate from behaviors idealized by microeconomic theories of expected utility, notably that while the commonly observed behavior choosing a certain gain with a lower value than the expected value of an uncertain gain can be explained to some degree by expected utility theory, the commonly observed behavior of choosing a gamble on losing outcomes with an expected loss of larger magnitude than a different certain loss cannot be explained by expected utility theory; this partly explains the risks that people take in business and can be explained in turn by how people in their perceptions tend to overestimate probabilities that are close to but not exactly 0 and underestimate probabilities that are close to but not exactly 1. Finally, the book partly explains notions of hedonic adaptation (the idea that one's sense of well-being is generally similar in many different good or bad medium- or long-term circumstances by adapting to those circumstances) by distinguishing how people rate pleasure or pain when experiencing those things versus in hindsight and shows how people's conceptions of their identities & well-being in the past, present, and future are intimately tied to their actual memories and their abilities to form & retain memories. These aspects of self-conception as well as perceptions of probability can also be tied to Systems 1 versus 2, as many seemingly shortsighted decisions or perceptions can be explained by System 1 making snap judgments lazily & using heuristics based on incomplete information.
Especially as I read the latter 40% of the book, I came to appreciate how many of the ideas of this book had permeated into other things that I had read & heard from others and that I had internalized into my own worldview & view of myself. Professionally, I could see how so many aspects of framing could be important when designing surveys & focus groups. Personally, I could see how especially as I have aged, I have in many cases consciously chosen to not worry too much about certain details and instead make decisions based on lazier heuristics because I didn't feel that the results of spending more mental energy making a decision based on System 2 would be worth the effort. At the same time, I have become more consciously aware of how my memories of things in my own life can be affected by the passage of time and by more recent events in my own life, and I have become more consciously aware of the deep entanglement between my perceptions of my own memories and the narratives that shape my perceptions of my own life & of the world. I thus feel more proud of maintaining detailed personal diaries where I take note (using System 2 as much as possible when considering things outside of the current moment) of how I feel about various things in the moment as well as in hindsight and carefully consider how & why my thoughts & feelings about different events in or aspects of my life have evolved over time. Moreover, I have become more aware over time of when I might be vulnerable (through System 1) to the power of suggestion or to a subconscious desire to align with groupthink, though given that it is System 1, I am not necessarily aware of these things until later (thinking about these things through System 2). Finally, especially over the last several years, I have come to see many things at a very broad conceptual/philosophical level, whether the experiences in my own life, the evolution of different aspects of human society, or the expansion of human knowledge, in terms of perdurantism [LINK from Wikipedia]; although I am not philosophically sophisticated enough to be able to think through & defend all of its implications, it intuitively makes sense to me to think about personal identities, feelings, people, and other things that can be said to exist, in terms of their existence in spacetime and not just in space at specific instants of time. Because of my philosophical inclination in this way, I was particularly pleased to see the author discuss the idea of time-integrated pleasure or pain and of looking at changing identities or overall life courses in terms of spacetime.
Although this book is not technical at the level of an academic journal article, it is fairly technical compared to most nonfiction books aimed at the general public, so I would say that it is aimed at a well-educated reader. That said, I do think that it is written with reasonable clarity for non-academic audiences. Additionally, the book covers many topics, and it is recommended to bear in mind the headings of sections that comprise groups of chapters, because otherwise, it is easy to lose track of the narrative of the book, especially because the book is long enough that I suspect that it would be impossible for most readers (even those who read books, including more technical nonfiction books, relatively quickly) to finish this book in one sitting. I would say that the concluding chapter is a nice way to reinforce the main points of the book in the reader's mind and that the details of each chapter can be treated as a reference when needed as opposed to forming a perfectly coherent narrative in the progression of chapters in the book.
It is important to remember that some aspects of this book are out of date. In some cases, that is just because this book was published in 2011 and had been written over many years before that; for example, the author gives an example of estimating the likelihood of choosing a particular major in college, but that example uses base rates that seem to be quite out-of-date. In other cases, the book is out of date because it is based on academic experimental work in psychology & behavioral economics, and other studies may find contradictory (either null or opposite) results to those presented in this book. The Wikipedia article about this book [LINK] discussed how most of the results from most of the studies discussed in one chapter (as an example) have been found to be not replicable, with the author afterwards admitting to putting too much faith in those studies and therefore falling prey to the same biases as those discussed in that chapter & elsewhere in the book. As a slightly different example, later parts of the book discuss the ideas of nudge theory and its seeming successes in public policy, but the Wikipedia article about nudge theory [LINK] has pointed out that later studies & meta-analyses have found that after correcting for publication biases in favor of positive results & against null results, nudging does not yield statistically significant (non-null) effects on human behavior; in this case, one of the primary researchers (who is named in this book as a collaborator of the author & pioneer of nudge theory) has made some counterarguments that I don't find convincing.
With these caveats in mind, I would still recommend this book to anyone interested in these ideas and with the patience to carefully consider them, though this may partly reflect my own biases in how I view issues of identity & the world. Follow the jump to see my other assorted & disjointed thoughts about this book.
In the first chapter, the author introduces Systems 1 & 2, and in the next few chapters, the author further fleshes them out. I got the sense that the fact that most thoughts, judgments, and actions come from System 1 does not necessarily mean that all thoughts, judgments, and actions come from System 1 and that there is no room for freely chosen thoughts from System 2 to go against System 1 (even if that is unlikely to happen or if the assumptions & judgments built into System 1 bias the parameters going into & restrict the parameter space of the freely chosen thoughts from System 2).
In the sixth chapter, the author describes research seeming to show why humans are psychologically predisposed to separate physical causality (like a hand physically moving to pick up an object) from intentional causality (like a person believing that something in that person's soul was responsible for the hand moving to pick up the object in the first place) and therefore why most traditional religions have concepts akin to a soul. However, I found some of these comments about religion to not be well-explained and to border upon circular reasoning.
In chapters between the seventh & fourteenth chapters, the author discusses misattribution of many seemingly random events (like having a supposedly "hot hand" in a sport) or risks (like supposedly being vulnerable to the extremely rare event of two airplanes colliding with each other). However, I wondered about how many of these events or risks that people face in their everyday lives are caused by or mediated by humans, so even in the absence of other systematic causal relations, if other humans as individuals or in groups are also motivated by erroneous judgments of statistical events and act accordingly, it is not obvious how one should really respond. Moreover, some seemingly rare problematic events (like airplanes having problems in flight) can turn out to be due to systematic problems (like the recent incidents with Boeing airplanes) that came about due to predictable errors in individual or group-based human judgment under a perverse system of incentives, so I wonder if some fears could be seen positively as motivating investigations into possible systematic causes. (The answer to the latter question may be that one must know when to stop investigating & to accept that the occurrence of a rare event may really just be due to chance and not any systematic cause, and it is hard to know with confidence where to draw that line.)
At various points in the book, the issue of ascribing success to skill versus luck arises. I figured that human lifespans are relatively short, such that any individual human might not have that many opportunities to do something for that long, so it is not clear to me what the right way is to ascribe certain things to skill or effort and other things to luck without falling into a trap of nihilism regarding the effects of one's own skill or efforts.
In the thirteenth chapter, the author describes how people tend to overestimate death rates from rare causes & underestimate death rates from common causes. While I now understand this to be an example of perceptions leading to overestimates of probabilities close to 0 & underestimates of probabilities close to 1, I also wonder if this could be due to genuine difficulty (in the sense of drawing a blank, not just feeling emotional horror) in imagining what it looks like to die of a common chronic disease versus imagining what it looks like to die in a dramatic event (like a lightning strike or airplane crash, especially if it has been portrayed at all in popular media irrespective of the specific frequency of portrayal of these forms of death compared to popular media portrayal other more common/mundane forms of death).
In the fifteenth chapter, the author describes how many people, including people who know probability theory and would avoid this mistake if the issue is presented like a classroom problem in purely mathematical terms, tend to believe that \( \mathrm{P}(\mathrm{A} \cap \mathrm{B}) \) may be larger than \( \mathrm{P}(\mathrm{A}) \) for events (sets) \( \mathrm{A} \) and \( \mathrm{B} \) even though that mathematically can never hold. The author ascribes this error to System 1 judging the situation based on plausibility & coherence without engaging System 2 to do a more careful analysis. However, I felt that just like in other books about similar ideas, there is essentially no consideration of whether people might actually be considering other related statistical quantities (even if incorrect), like either \( \mathrm{P}(\mathrm{A}|\mathrm{B}) \) or the ratio of the generalized distance of a specific example of the set \( \mathrm{A} \cap \mathrm{B} \) from the centroid of that set to the generalized distance of a specific example of \( \mathrm{A} \) from its centroid, and logically correctly following that chain of reasoning, when being asked to compare \( \mathrm{P}(\mathrm{A} \cap \mathrm{B}) \) to \( \mathrm{P}(\mathrm{A}) \).
In the sixteenth chapter, the author discusses the reluctance of people who are physically close to each other in a given moment to help someone else experiencing acute distress nearby. I wonder if this can be explained by not only an intellectually-derived feeling of a diffusion of responsibility across the group (dividing into much lower senses of responsibility for each individual in that group) but also an amplification/cascade of fear & uncertainty (both significantly affecting System 1) communicated subconsciously among members of that group via facial expressions, body language, vocal tones, reactive behavior, and related things.
In the nineteenth chapter, the author discusses the seemingly paradoxical fact that analysis in hindsight of a series of events with limited information can be most accurate by ascribing many events to luck and yet are most often explained by ordinary individuals using specific narratives that emphasize the roles of skill, talent, and hard work, and de-emphasize the role of luck. I wonder if this can also be explained by people intuitively understanding that situations with few data points should be explained with only a few parameters but then fooling themselves with Occam's razor into believing that the mere fact that an explanation that has a small number of parameters is necessary & sufficient to make that explanation compelling.
In the twentieth & twenty-first chapters, the author discusses how many experts who judge things (like stock traders trying to figure out when to buy or sell or wine tasters judging wine quality) are less accurate in many cases than simple heuristic formulas yet more confident of their own greater accuracy or of themselves being exempt from biases that supposedly only affect other human judges of these things. However, I wonder how one is supposed to draw the line between using qualitative expert judgments to tweak those formulas versus going too far with relying on inaccurate qualitative judgments. (Perhaps this can be partly answered by whether the values of coefficients associated with such quantified variables are statistically significantly different from the null hypothesis predictions.) Additionally, it seems odd for the author to claim the superiority of simple formulas to biased expert judgments while simultaneously appealing to common sense (and not much else) when developing such formulas. Finally, the author's optimism about algorithms may be countered by the book Weapons of Math Destruction by Cathy O'Neil (which I have reviewed in this blog [LINK]), and the concerns about liability could explain subpar performance of experts & doubts about the systematic misbehaviors of algorithms (with respect to specific societal priorities).
In the thirty-sixth chapter, the author explains the distinction between experience versus memory without resorting to the idea of hedonic adaptation. However, I think the author unduly discounts the idea that questions involving hypothetical scenarios of everlasting pleasure or pain that will never diminish in feeling are badly formed because most people might not be able to conceive of future in which they can't instinctively hedonically adapt to new circumstances, even if they can't articulate this issue in these terms. Moreover, I think that the author errs by not acknowledging that many people may subconsciously (without necessarily being able to articulate this) believe that experiences are meaningless without personal memories of them and that there is a nonlinear self-amplification effect in which a person's time-integrated perceived quality of life is higher or lower based on retention of memories of pleasurable or painful experiences, respectively.
In the thirty-seventh chapter, the author says based on empirical findings that "happiness is the experience of spending time with people you love and who love you". I found this to deeply resonate with my own experiences & perceptions of myself.
In the concluding chapter, the author discusses how many people prefer brief intense bursts of pleasure over moderately extended periods of happiness even if the time-integrated happiness is higher in the latter case than in the former case and how many people contrapositively prefer moderately extended periods of sadness over brief intense bursts of pain even if the time-integrated sadness is of a higher magnitude in the former case than in the latter case. It is worth noting the inconsistency in people's perceptions (which is not an inconsistency in the author's arguments but instead reinforces the author's arguments about seeming logical inconsistencies in people's beliefs), as they would prefer moderate extended periods of sadness over brief intense bursts of pain but would prefer to gamble on potentially bigger losses instead of taking moderate losses with certainty and they would prefer brief intense bursts of pleasure over moderate extended periods of happiness but would prefer to take certain moderate gains with certainty instead of gambling on potentially bigger gains. Moreover, it seems to me like many religions, especially philosophical traditions of Hinduism that follow the Bhagavadgītā as well as Buddhism, exhort their followers to find moderate happiness sustained over long periods of time that can bring a high value of time-integrated happiness by not excessively chasing after brief intense bursts of pleasure and not excessively avoiding brief intense bursts of pain, as the latter two behaviors would instead lead to the rut of settling for moderate sadness sustained over long periods of time yielding a high absolute value of time-integrated sadness.
More broadly, I appreciated that the author made clear that the facts that System 1 usually takes over and that people often have seemingly logically inconsistent behaviors & beliefs does not mean that all is lost or that there aren't ways to build systems (whether literal machines or organizational structures) that can guide humans toward decisions that work better on individual & group bases. As examples, systems (technologies as well as procedures) to fly airplanes are meant to minimize risks to safety that could be commonplace if pilots were not shielded from impulses generated by System 1, and democratic political systems with checks & balances of power can prevent falling into traps set by System 1 (as long as all participants believe in those systems). However, I wonder how far this can go and whether turning progressively more decisionmaking over to AI systems will lead to a backlash in which those decisions, even if generally better than human decisions from the perspective of the known objective but clashing against objectives that are subconsciously held but consciously unknown or leading to harm for some specific groups of people, may be seen as so alien to human reasoning that humans will not let those systems continue to make decisions.
