What is *Rationality: What It Is, Why It Seems Scarce, Why It Matters* about?

Steven Pinker’s *Rationality* examines how humans can improve decision-making by understanding logic, probability, and cognitive biases. It argues that while humans evolved rational capacities, modern challenges like misinformation require deliberate use of critical thinking tools. The book explores game theory, Bayesian reasoning, and societal applications, positioning rationality as essential for solving global issues like climate change and political polarization.

Who should read *Rationality* by Steven Pinker?

This book suits critical thinkers, educators, policymakers, and anyone seeking to navigate misinformation or improve decision-making. It’s valuable for readers interested in psychology, behavioral economics, or the science of reason, offering practical frameworks for addressing personal and societal challenges.

Is *Rationality* worth reading in 2025?

Yes—Pinker’s insights remain vital for countering misinformation, conspiracy theories, and polarized discourse. By dissecting cognitive biases and offering tools like probabilistic reasoning, the book equips readers to make clearer decisions in an increasingly complex world.

What are the key concepts in *Rationality*?

Pinker emphasizes **epistemic rationality** (aligning beliefs with evidence) and **instrumental rationality** (achieving goals effectively). He explores Bayesian reasoning, game theory, and statistical fallacies, advocating for these tools to address issues from climate policy to personal finance.

How does Steven Pinker define rationality?

Pinker defines rationality as using logic, probability, and evidence to form accurate beliefs (**epistemic**) and make decisions that maximize desired outcomes (**instrumental**). He contrasts this with irrationality driven by cognitive biases or motivated reasoning.

What critiques does Pinker offer about human decision-making?

Pinker challenges the notion that humans are inherently irrational, arguing instead that biases like confirmation bias or the availability heuristic stem from evolutionary mismatches. He stresses that rationality can be cultivated through education and critical thinking.

How does *Rationality* address societal challenges?

The book applies rational frameworks to global issues, advocating for evidence-based policymaking, scientific literacy, and Bayesian reasoning to combat misinformation. Pinker argues that collective rationality is crucial for solving climate change, inequality, and geopolitical conflicts.

What is “rational irrationality” in *Rationality*?

Rational irrationality refers to strategically adopting irrational beliefs for personal gain, such as politicians stoking conspiracy theories to mobilize supporters. Pinker warns this undermines societal progress but notes it can be countered through institutional safeguards.

21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩

それが何であるか、なぜ不足しているのか、そしてどのように増やすか

スティーブン・ピンカー

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『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の概要

『合理的思考（Rationality）』の中で、スティーブン・ピンカーは私たちの精神における最大のパラドックスに取り組んでいます。それは、論理的思考能力を持つ人間が、なぜ頑なに不合理であり続けるのかという問いです。ベイズ推定への親しみやすいアプローチについてコロンビア大学のアンドリュー・ゲルマンからも称賛された2021年のこのベストセラーは、合理性が単なる学問上の問題ではなく、私たちの文明にとって最も重要な生存スキルである理由を明らかにしています。

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第1章

The Paradox of Our Time: Why Rationality Matters Now More Than Ever

In an era when we have unprecedented access to information and scientific knowledge, our public discourse seems increasingly dominated by conspiracy theories, fake news, and "post-truth" rhetoric. Steven Pinker's "Rationality" arrives at this critical juncture, offering a compelling case for reason in an apparently unreasonable world. The book has garnered praise from intellectual heavyweights like Bill Gates, who called it "the most important book of our time," and has become required reading in university courses across disciplines. What makes this work particularly timely is how it bridges the gap between our remarkable scientific achievements-like developing COVID vaccines in record time-and our collective struggle to apply rational thinking to pressing social problems. Pinker, with his characteristic blend of scientific rigor and accessible prose, doesn't just lament our cognitive shortcomings but provides a toolkit for overcoming them, making this book both a diagnosis of and potential cure for our current epistemic crisis.

第2章

The Rational Animal: Our Cognitive Achievements and Limitations

Homo sapiens means "wise hominin," and in many ways, we've earned this title. Our species has dated the universe's origin, decoded life's secrets, unraveled consciousness, and chronicled our history. We've applied this knowledge to enhance human flourishing, extending lifespans from thirty to over seventy years, reducing extreme poverty from ninety to less than nine percent of humanity, and dramatically decreasing deaths from war and famine. Even when facing new pandemics, we can identify causes within days, sequence genomes within weeks, and develop vaccines within a year. Yet despite these achievements, we struggle with seemingly simple reasoning problems. Consider the bat and ball problem: "A bat and ball cost $110 in total. The bat costs $100 more than the ball. How much does the ball cost?" Most people immediately answer $10, but that would make the bat cost $110, for a total of $120. The correct answer is $5 (with the bat costing $105). Similarly, in the Wason selection task testing logical reasoning, only 10% of participants correctly identify which cards must be checked to test an "if-then" rule. Our probability intuitions fare no better. In the Monty Hall problem, where contestants choose between three doors with a prize behind one, most people fail to recognize that switching doors after one empty door is revealed doubles their chances of winning. Even professional mathematicians like Paul Erdos initially rejected this counterintuitive solution. These cognitive illusions don't indicate a fundamentally broken reasoning system but reveal how our minds prioritize socially useful interpretations over mathematical precision. Just as visual illusions show how our visual system optimizes for real-world accuracy rather than technical precision, cognitive illusions demonstrate how our reasoning systems favor practical interpretations over literal correctness. Our cognitive systems, like our visual ones, are marvels of evolution-not fundamentally flawed, but optimized for different priorities than technical accuracy. However, just as pilots must learn to trust instruments over visual intuitions when flying in clouds, we must learn when to override our intuitive reasoning with formal tools of logic, probability, and critical thinking. In the modern world, thinking "by the seat of our pants" can send our democracy into a fatal error pattern similar to what killed inexperienced pilots who trust their feelings over their instruments.

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『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の一語一語が音声に合わせてリアルタイムでハイライトされ、自然に読み進められます。

第3章

Rationality's Image Problem: The Case for Reason

Rationality has an image problem in contemporary culture. Being labeled a "nerd," "wonk," or "geek" implies social deficiency, while Hollywood and popular music celebrate escape from reason as the path to freedom and joy. Even academic movements like postmodernism treat rationality as merely a social construction that justifies privilege. Despite this cultural disdain, rationality-defined as "the ability to use knowledge to attain goals"-deserves our allegiance. The case for rationality seems obvious: if you want things, rationality helps you get them. While we can't provide an ultimate justification for reason without circular reasoning (as Lewis Carroll illustrated in "What the Tortoise Said to Achilles"), we commit to reason by engaging in argument itself. As Thomas Nagel noted, rejecting rationality is self-defeating-if you claim rationality is unnecessary, either your statement is irrational (so I needn't believe it) or rational (contradicting your claim). Contrary to popular misconception, rationality doesn't oppose emotion or creativity. David Hume's famous statement that "reason is the slave of the passions" doesn't advocate impulsivity but recognizes that reason is a means to ends determined by our desires and feelings. It's neither rational nor irrational to prefer chocolate ice cream to maple walnut, or to fall in love, keep gardens, or care for stray dogs. These preferences operate in domains where reason serves rather than dictates our aims. Many apparent irrationalities actually reflect conflicts between multiple goals or different time frames. The famous marshmallow test (one now or two later) exemplifies the dilemma between immediate small rewards versus delayed larger ones. While some discounting of future rewards is rational (the future is uncertain; "a bird in hand is worth two in the bush"), people often discount irrationally by preferring smaller immediate rewards over much larger delayed ones, or by reversing preferences as rewards get closer in time. Sometimes it's even rational to choose ignorance or incapacity. We avoid spoilers for movies to preserve suspense and enjoyment. The Brink's truck driver who "does not know combination to safe" can't be coerced into revealing it. In Thomas Schelling's paradoxes of reason, sometimes it's rational to be powerless or even irrational-like visibly removing your ability to swerve in a game of Chicken, forcing your opponent to yield. Even morality can be grounded in reason through three simple premises: self-interest (we prefer good things happen to us), sociality (we live with others whose actions affect us), and impartiality (the logical recognition that "I" and "you" are interchangeable perspectives). From these premises emerges the Golden Rule and its variants across cultures and religions.

第4章

The Tools of Logic: Formal Rules and Human Reasoning

Logic forms the foundation of rational argument, allowing us to infer true conclusions from true premises. Despite logic's power, we haven't achieved Leibniz's dream of settling disagreements by simply calculating. This failure stems from three challenges: logic can be difficult even for logicians, people often don't follow logical rules, and logic is a tool suited only for certain goals with certain kinds of knowledge. Formal logic deals with the structure of statements rather than their content, focusing on how they're assembled using subjects, predicates, and logical connectors like "and," "or," "not," and "if-then." The power of logic comes from rules of valid inference-algorithms that allow leaping from true premises to true conclusions. These include modus ponens ("If P then Q; P; therefore Q"), modus tollens ("If P then Q; not Q; therefore not P"), and others. Common formal fallacies include affirming the consequent ("If P then Q; Q; therefore P") and denying the antecedent. These errors appear in political rhetoric, crackpot claims about geniuses being laughed at, and assumptions about college dropouts becoming tech billionaires. Formal reconstruction helps identify these fallacies by unpacking arguments into explicit premises and conditionals. While formal fallacies violate specific rules of logic, informal fallacies exploit psychologically compelling but intellectually spurious reasoning. Many informal fallacies stem from our deep-seated desire to win arguments-a feature so fundamental that cognitive scientists Dan Sperber and Hugo Mercier suggest it was the evolutionary pressure that developed human reasoning. Common informal fallacies include the straw man (misrepresenting an opponent's position), special pleading (making exceptions to one's own rules), moving the goalposts (changing definitions when challenged), and the no-true-Scotsman fallacy (excluding counterexamples by definition). Logic will never completely rule our reasoning because logical propositions differ fundamentally from empirical ones. Logical truths (what Hume called "relations of ideas") can be determined by analyzing definitions and checking truth tables-like verifying "all bachelors are unmarried." Empirical truths ("matters of fact") require observation-like discovering that not all swans are white when finding black ones in New Zealand. Additionally, most human concepts don't fit classical logic's requirement for necessary and sufficient conditions. As Wittgenstein famously demonstrated, try defining "game"-no single feature unites board games, sports, children's play, and card games. Instead, our concepts work by "family resemblance," where members share overlapping features rather than essential defining traits. Human rationality is a hybrid system combining pattern association with logical symbol manipulation. This logical reasoning enables our highest achievements-science, morality, and law-by freeing us from similarity and stereotypes.

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第5章

Probability and Randomness: Navigating an Uncertain World

Rationality requires dealing with randomness and uncertainty. "Randomness" refers to both a lack of pattern in data and unpredictability in processes. While quantum mechanics may introduce true randomness at subatomic scales, our everyday experience of randomness comes from two sources: the butterfly effect in chaotic systems, where tiny unmeasurable differences in initial conditions produce enormous differences in outcomes, and complexity-when outcomes depend on numerous tiny causes impossible to track (like in a coin flip), the result appears random from a human perspective. Probability has multiple interpretations that often align but sometimes diverge, causing confusion and controversy. These include classical (counting favorable outcomes divided by total outcomes), propensity (physical disposition of objects), subjectivist/Bayesian (quantifying belief from 0 to 1), evidential (degree to which information warrants a conclusion), and frequentist (proportion of outcomes in many repetitions). While probability is fundamentally about events as a proportion of opportunities, humans rarely calculate it this way. Instead, we rely on the "availability heuristic"-judging probability by how easily examples come to mind. This mental shortcut works reasonably well when our memories accurately reflect frequencies, but fails when our impressions are distorted by media coverage, recency, vividness, or emotional impact. The media functions as an "availability machine," serving up anecdotes that distort our understanding of prevalence. News, by definition, reports what happens rather than what doesn't happen, making the denominator in probability calculations invisible and biasing us toward the morbid and sudden rather than gradual improvements. This availability-driven ignorance creates measurable misperceptions: people consistently believe crime is rising during periods of decline and think global indicators of well-being are worsening when they're improving. When calculating probabilities of multiple events, we must understand how they combine. For disjunctions (OR relationships), the probability equals the sum of individual probabilities minus their overlap. For complements (NOT relationships), the probability is simply 1 minus the original probability. Conditional probabilities-the probability of A given B-cause endless confusion despite their simple formula: prob(A|B) = prob(A AND B)/prob(B). People frequently make three critical errors: confusing base rates with conditional probabilities (like thinking overall lightning strike probability equals the probability during storms); failing to enumerate all possibilities (as in the Boy or Girl paradox where the probability of two girls given at least one girl is 1/3, not 1/2); and most dangerously, reversing conditionals-confusing prob(A|B) with prob(B|A). This last error appears in the prosecutor's fallacy, where the probability of matching evidence given innocence gets confused with the probability of innocence given matching evidence.

第6章

Bayesian Reasoning: Updating Beliefs with Evidence

The Rationality Community stands as a hopeful counterpoint to the general disdain for reason in online discourse. These individuals strive to be "less wrong" by acknowledging their cognitive biases and embracing critical thinking standards. At the heart of their approach is Bayes' rule-the mathematical law governing how we should update our beliefs when encountering new evidence. When doctors assess a positive cancer test result as indicating an 80-90% chance of disease (when the actual probability is only 9%), they're demonstrating base-rate neglect-a major flaw in our Bayesian reasoning. We fixate on the positive test (the likelihood) while forgetting the disease's rarity (the prior). Instead of proper Bayesian calculation, we rely on the representativeness heuristic-judging probability by similarity to stereotypes rather than statistical reality. Prior credence isn't prejudice or dogma but accumulated knowledge from past experience. In Bayesian updating, yesterday's posterior probability becomes today's prior. This explains why skepticism toward paranormal claims is rational rather than close-minded-as Francis Crick noted, "Any theory that can account for all the facts is wrong, because some of the facts are wrong." Hume's argument against miracles is thoroughly Bayesian: extraordinary claims require extraordinary evidence. When measuring any socially significant variable and breaking it down by demographics like race or gender, the averages are never identical. This creates a dilemma: a good Bayesian would use these base rates for accurate predictions about individuals, essentially engaging in profiling. Yet most people are horrified by this, and for good reason. While actuarial prediction might favor using all available information, higher goals like fairness, building social trust, avoiding self-fulfilling prophecies, and signaling commitment to equality justify forbidding the use of demographic base rates in many contexts. For all our taboos and neglects, we aren't hopelessly un-Bayesian. When problems are reframed using "natural frequencies" instead of decimal fractions, people's Bayesian reasoning improves dramatically-87% of doctors get the breast cancer screening problem right versus 15% with the original wording. Visual representations make Bayesian reasoning even more intuitive. Rather than writing people off as irrational, we should enhance their existing rationality through better education in risk literacy, especially for professionals whose decisions affect our lives.

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第7章

Making Rational Choices: Risk, Reward, and Human Decision-Making

Rational choice theory is widely misunderstood and maligned as claiming humans are selfish psychopaths or hyper-rational calculators. In reality, it's a mathematical theorem about decision consistency with no direct implications for how humans actually think. The theory, formalized by von Neumann and Morgenstern in 1944, defines rationality as making choices consistent with one's goals. Rational choice theory rests on seven axioms that together lead to expected utility theory: rational deciders must assess outcomes on a continuous scale, multiply by probability, and choose the option with highest expected utility. Utility isn't about self-interest or hedonism but whatever values a person consistently maximizes. The theory doesn't dictate values but offers guidance on not squandering them. Money's relationship to utility isn't linear but concave, showing diminishing marginal utility-an extra hundred dollars increases a poor person's happiness more than a rich person's. This explains risk aversion: people buy insurance because a small certain loss causes less utility reduction than the risk of a catastrophic loss. However, the theory struggles to explain why people also gamble, suggesting either irrationality, entertainment value, or a second bend in the utility curve where jackpots promise entry to a different lifestyle. People violate rational choice axioms in several ways. With Commensurability, they resist putting prices on sacred values like endangered species or human lives. Herbert Simon's concept of bounded rationality acknowledges that real humans have limited information, time, and memory. Instead of optimizing, people must satisfice-settle for options that are "good enough"-which can lead to violations of axioms like Transitivity. People's choices flip dramatically based on how risks and rewards are framed. When presented with identical final outcomes, people are risk-averse for gains (preferring a guaranteed $500 over a 50% chance at $1,000) but risk-seeking for losses (preferring a 50% chance of losing $1,000 over a guaranteed loss of $500). This reveals that people aren't consistently risk-averse-rather, they're loss-averse, willing to take risks specifically to avoid losses. While cognitive scientists and behavioral economists have made careers demonstrating how people violate rational choice axioms, we're often better off when our decisions align with expected utility calculations. Many everyday decisions would improve through basic probability-times-outcome thinking: extended warranties on appliances are typically terrible deals; low insurance deductibles rarely make mathematical sense; medical screening decisions become clearer when weighing true benefits against false positives.

第8章

Signal Detection: Balancing False Alarms and Missed Opportunities

Rationality requires distinguishing what is true from what we want to be true, resisting wishful thinking even as we navigate an uncertain world. Signal Detection Theory offers a rational approach by combining Bayesian reasoning with rational choice-estimating probabilities and weighing expected costs and benefits. The fundamental challenge is determining whether an indicator represents a genuine signal or merely noise in our perception. Statistical distributions help us understand how to interpret erratic indicators of reality. Bell curves arise when measurements vary randomly around an average value, appearing whenever a measurement comes from many small causes. But our observations are always contaminated by noise, creating overlapping distributions between signal and noise. We must set a criterion to decide whether to say "Yes" (signal) or "No" (noise), which creates four possible outcomes: hits (correctly identifying signals), false alarms (saying "Yes" to noise), misses (failing to detect signals), and correct rejections (properly ignoring noise). The rational way to set a detection criterion depends on the benefits of correct decisions and costs of errors. A rational observer sets a higher criterion when noise is more common than signals, when hits yield smaller rewards, when correct rejections bring greater benefits, when false alarms are costly, or when misses are less catastrophic. While signal detection always forces tradeoffs between misses and false alarms, we can mitigate this tragedy by increasing the sensitivity of our observations. The costs depend on both our response bias (where we set the cutoff) and sensitivity (d'), which measures how far apart the signal and noise distributions are. By perfecting our detection systems to better distinguish signals from noise-pushing the bell curves farther apart-we achieve both fewer misses and fewer false alarms regardless of where we set our criterion. Legal proceedings exemplify signal detection problems, where evidence about a defendant's guilt varies in strength and overlaps more than most realize. We traditionally set a high criterion ("guilty beyond reasonable doubt"), following Blackstone's principle that "It is better that ten guilty persons escape than that one innocent suffer." But our moral aspirations likely outstrip our probative powers-meeting our ethical standards would require evidence from guilty defendants to be 3-5 standard deviations stronger than from innocent ones, far beyond typical forensic sensitivity. Statistical significance testing operates on the same principles as signal detection theory. When scientists analyze data, they must distinguish between real effects (signals) and sampling error (noise). Most scientists fundamentally misunderstand what statistical significance actually means. A p-value below .05 doesn't indicate the probability that the null hypothesis is true, that there is a 95% chance of an effect, or that you'd replicate the finding 95% of the time. These are all posterior probabilities, while p-values are likelihoods-the probability of obtaining the data given the hypothesis.

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』をもっと深く楽しむ

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言葉をハイライトして音声と同期
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第9章

The Rationality Challenge: Overcoming Biases in a Post-Truth Era

Despite human reasoning's vulnerabilities, we need not surrender to irrationality. The arc of knowledge bends toward rationality-few people today believe in werewolves, bloodletting, or divine omens that were mainstream centuries ago. Most people can judge headline veracity reasonably well and change their minds when presented with clear corrections. Our susceptibility to pseudoscience and paranormal beliefs stems from deep cognitive intuitions. As intuitive dualists, we readily accept that minds can exist separately from bodies, leading to beliefs in telepathy, ghosts, and souls. As essentialists, we sense invisible substances in living things, making us receptive to homeopathy and suspicious of vaccines. As teleologists, we see purpose in complexity, embracing creationism and astrology. Viral misinformation and fake news thrive because they're fundamentally entertaining. They feature compelling narrative elements of sex, violence, revenge, danger, fame, and taboo-the same features that make urban legends and fiction culturally attractive. Headlines like "FBI Agent Suspected in Hillary Email Leaks Found Dead in Apparent Murder-Suicide" succeed because they would make excellent plots for suspense thrillers. Conspiracy theories flourish because humans evolved to be vigilant against real conspiracies. Throughout human history, from tribal warfare to modern politics, stealthy plots by enemy coalitions have been genuine threats. In signal detection terms, missing a real conspiracy costs more than false-alarming to a suspected one, so we're biased toward the trigger-happy end of the scale. To strengthen our cognitive immune systems, we should valorize rationality itself, making it socially rewarding to question dogmas and change minds when facts change. Universities must restore trust by ending their suffocating monocultures that punish questioning of certain dogmas. The press should embrace viewpoint diversity, critical thinking, and statistical literacy, implementing fact-checking and avoiding false balance between experts and cranks. Educational institutions should make rationality "the fourth R" alongside reading, writing and arithmetic, with well-designed courses that train students to spot cognitive biases in real-life settings. Rationality is a public good requiring protection from the Tragedy of the Commons where each person prefers their truth while collectively we need the truth. Successful institutions of rationality never depend on individual brilliance but on feedback systems that make the whole smarter than its parts. Social media platforms must redesign their incentive structures to stop rewarding dangerous falsehoods, while other institutions from journalism to governance should implement mechanisms that give disinterested truth an edge over myside bias. Rationality is ultimately not just cognitive but moral-requiring the same impartiality that lies at the core of ethics.

第10章

Why Rationality Matters: The Stakes for Our Future

Cognitive biases extract real costs in our everyday lives. We discount the future myopically, sacrificing larger future rewards for quick highs. We throw good money after bad by trying to recoup sunk costs. We avoid safe planes for dangerous cars based on availability bias. We save too little for retirement due to blind spots about exponential growth, and invest in expensive managed funds that underperform simple indexes. Research confirms that rational thinking skills protect against life's mishaps. A study measuring reasoning competence (avoiding fallacies like overconfidence, sunk costs, and framing effects) found that better reasoners suffered fewer negative life outcomes like accidents, financial losses, and unwanted pregnancies. This relationship held true even when controlling for intelligence and socioeconomic status, suggesting that rationality itself provides protection against misfortune. Human progress is an empirical fact hidden by availability bias. When we examine trend lines rather than headlines, we see humanity is healthier, wealthier, longer-lived, better fed, better educated, and safer than in centuries past. This progress isn't driven by some mystical force but by rationality-humans applying ingenuity through institutions that pool collective intelligence. Progress extends beyond material well-being to how we treat each other. Cruel practices like human sacrifice, slavery, despotism, blood sports, sadistic punishments, and various forms of persecution and oppression have declined significantly throughout history. Surprisingly, reasoned arguments often served as the first domino in moral progress. Philosophers would write treatises explaining why certain practices were indefensible or inconsistent with widely-held values. These arguments would spread, be debated in public spaces, influence leaders and legislators, and eventually become absorbed into society's conventional wisdom. Sound arguments alone cannot improve the world, but they guide movements for change, making the difference between moral force and brute force. They reveal moral blights and help discover feasible remedies, ensuring moral progress continues. The equality of sentient beings, grounded in the logical irrelevance of distinguishing between "me" and "you," is an idea people throughout history rediscover and extend to new living things, expanding our circle of sympathy. This power of rationality to guide moral progress connects directly to its ability to guide material progress and wise life choices. Our well-being and capacity for goodness depend on grasping impartial principles that transcend our limited personal experience, awakening us to ideas and realities that may confound our intuitions but are true nonetheless.

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100万人以上の学習者に愛用されています

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『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の主要テーマ

cognitive biases
critical thinking tools
probabilistic reasoning
epistemic crisis
logic and fallacies

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の名言

Rationality is the ability to use knowledge to attain goals.
Rejecting rationality is self-defeating.
Rationality has an image problem.
Reason is the slave of the passions.
Sometimes it's even rational to choose ignorance.

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の登場人物

Steven PinkerAuthor and cognitive scientist
Paul ErdosMathematician who struggled with Monty Hall
David HumePhilosopher who discussed reason and passions
Thomas NagelPhilosopher who argued for the necessity of reason
Thomas SchellingThinker who explored the paradoxes of rationality

著者について

『合理性（Rationality）』の著者であるスティーブン・ピンカーは、言語、人間の認知、そして合理的思考の基盤を探求する、著名な認知心理学者であり、ベストセラー作家、ハーバード大学教授です。ノンフィクション作品『言語を生みだす本能（The Language Instinct）』と『心の仕組み（How the Mind Works）』で2度のピューリッツァー賞ファイナリストに選ばれたピンカーは、進化心理学、言語学、そして啓蒙思想を橋渡しし、現代の言説における理性の重要性を提唱しています。

『啓蒙思想21世紀（Enlightenment Now）』や『暴力の人類史（The Better Angels of Our Nature）』を含む彼の著書は20以上の言語に翻訳され、第一線の公共的知識人としての地位を確固たるものにしました。

ピンカーの洞察は、マサチューセッツ工科大学（MIT）やハーバード大学での学術的役割に根ざしており、そこでは心理学部の学部長や認知神経科学のディレクターを務めました。NPR、『ザ・コルベア・レポー（The Colbert Report）』、TEDトークに頻繁にゲスト出演し、複雑な科学的概念を幅広い層に向けた分かりやすい分析へと昇華させています。2022年のBBVA財団フロンティア・オブ・ナレッジ・アワードの受賞は、人類の進歩と合理性の理解における彼の世界的な影響力を強調するものです。

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Irrationality

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The Rational Optimist

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The Stuff of Thought

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Determined

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Why Smart People Think Irrationally の書籍表紙

18 sources

Why Smart People Think Irrationally

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Combat logical fallacies

In an era of misinformation, the ability to think critically is a vital survival skill. This plan is designed for professionals, students, and citizens who want to sharpen their decision-making and resist manipulation in complex public and private debates.

5 h 25 m•4 セクション

学習プラン

The Laws of Human Nature

In an era of constant social interaction, understanding the hidden forces that drive human behavior is a vital competitive advantage. This plan is designed for leaders, negotiators, and anyone seeking to improve their interpersonal dynamics and self-mastery.

1 h 30 m•3 セクション

学習プラン

The Science of High-Stakes Decisions

In high-pressure environments, biological stress responses often override rational thought, leading to costly errors. This course is essential for leaders and professionals who need to maintain peak performance and logical consistency when the stakes are highest.

1 h 30 m•3 セクション

学習プラン

Understand psychology

This plan offers a comprehensive look at the human experience, from internal cognition to social interaction. It is ideal for anyone seeking to improve their emotional intelligence or pursue a career in behavioral sciences.

4 h 46 m•4 セクション

コロンビア大学卒業生がサンフランシスコで開発

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@Chloe, Solo founder, LA

117

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@Raaaaaachelw

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@Matt, YC alum

108

"Reading used to feel like a chore. Now it’s just part of my lifestyle."

@Erin, Investment Banking Associate , NYC

254

"Feels effortless compared to reading. I’ve finished 6 books this month already."

@djmikemoore

"BeFreed turned my guilty doomscrolling into something that feels productive and inspiring."

@Pitiful

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"BeFreed turned my commute into learning time. 20-min podcasts are perfect for finishing books I never had time for."

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"BeFreed replaced my podcast queue. Imagine Spotify for books — that’s it. 🙌"

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201

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@OojasSalunke

"The themed book list podcasts help me connect ideas across authors—like a guided audio journey."

@Leo, Law Student, UPenn

483

"Makes me feel smarter every time before going to work"

@Cashflowbubu

BeFreedがウェブ上でどのように話題になっているかをもっと見る

コロンビア大学卒業生がサンフランシスコで開発

LOVED BY

1,000,000+ curious minds.

4.7

avg rating

1M+ learners

"Instead of endless scrolling, I just hit play on BeFreed. It saves me so much time."

@Moemenn

"I never knew where to start with nonfiction—BeFreed’s book lists turned into podcasts gave me a clear path."

@Chloe, Solo founder, LA

117

"Perfect balance between learning and entertainment. Finished ‘Thinking, Fast and Slow’ on my commute this week."

@Raaaaaachelw

"Crazy how much I learned while walking the dog. BeFreed = small habits → big gains."

@Matt, YC alum

108

"Reading used to feel like a chore. Now it’s just part of my lifestyle."

@Erin, Investment Banking Associate , NYC

254

"Feels effortless compared to reading. I’ve finished 6 books this month already."

@djmikemoore

"BeFreed turned my guilty doomscrolling into something that feels productive and inspiring."

@Pitiful

4.5K

"BeFreed turned my commute into learning time. 20-min podcasts are perfect for finishing books I never had time for."

@SofiaP

"BeFreed replaced my podcast queue. Imagine Spotify for books — that’s it. 🙌"

@Jaded_Falcon

201

"It is great for me to learn something from the book without reading it."

@OojasSalunke

"The themed book list podcasts help me connect ideas across authors—like a guided audio journey."

@Leo, Law Student, UPenn

483

"Makes me feel smarter every time before going to work"

@Cashflowbubu

"Instead of endless scrolling, I just hit play on BeFreed. It saves me so much time."

@Moemenn

"I never knew where to start with nonfiction—BeFreed’s book lists turned into podcasts gave me a clear path."

@Chloe, Solo founder, LA

117

"Perfect balance between learning and entertainment. Finished ‘Thinking, Fast and Slow’ on my commute this week."

@Raaaaaachelw

"Crazy how much I learned while walking the dog. BeFreed = small habits → big gains."

@Matt, YC alum

108

"Reading used to feel like a chore. Now it’s just part of my lifestyle."

@Erin, Investment Banking Associate , NYC

254

"Feels effortless compared to reading. I’ve finished 6 books this month already."

@djmikemoore

"BeFreed turned my guilty doomscrolling into something that feels productive and inspiring."

@Pitiful

4.5K

"BeFreed turned my commute into learning time. 20-min podcasts are perfect for finishing books I never had time for."

@SofiaP

"BeFreed replaced my podcast queue. Imagine Spotify for books — that’s it. 🙌"

@Jaded_Falcon

201

"It is great for me to learn something from the book without reading it."

@OojasSalunke

"The themed book list podcasts help me connect ideas across authors—like a guided audio journey."

@Leo, Law Student, UPenn

483

"Makes me feel smarter every time before going to work"

@Cashflowbubu

"Instead of endless scrolling, I just hit play on BeFreed. It saves me so much time."

@Moemenn

"I never knew where to start with nonfiction—BeFreed’s book lists turned into podcasts gave me a clear path."

@Chloe, Solo founder, LA

117

"Perfect balance between learning and entertainment. Finished ‘Thinking, Fast and Slow’ on my commute this week."

@Raaaaaachelw

"Crazy how much I learned while walking the dog. BeFreed = small habits → big gains."

@Matt, YC alum

108

"Reading used to feel like a chore. Now it’s just part of my lifestyle."

@Erin, Investment Banking Associate , NYC

254

"Feels effortless compared to reading. I’ve finished 6 books this month already."

@djmikemoore

"BeFreed turned my guilty doomscrolling into something that feels productive and inspiring."

@Pitiful

4.5K

"BeFreed turned my commute into learning time. 20-min podcasts are perfect for finishing books I never had time for."

@SofiaP

"BeFreed replaced my podcast queue. Imagine Spotify for books — that’s it. 🙌"

@Jaded_Falcon

201

"It is great for me to learn something from the book without reading it."

@OojasSalunke

"The themed book list podcasts help me connect ideas across authors—like a guided audio journey."

@Leo, Law Student, UPenn

483

"Makes me feel smarter every time before going to work"

@Cashflowbubu

BeFreedがウェブ上でどのように話題になっているかをもっと見る

今すぐ学習の旅を始めよう

第8章

21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩

概要『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の概要

1冊の本。さまざまな聴き方。

The Paradox of Our Time: Why Rationality Matters Now More Than Ever

The Rational Animal: Our Cognitive Achievements and Limitations

聴きながら、すべての言葉を目で追えます

Rationality's Image Problem: The Case for Reason

The Tools of Logic: Formal Rules and Human Reasoning

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』をもっと深く楽しむ

Probability and Randomness: Navigating an Uncertain World

Bayesian Reasoning: Updating Beliefs with Evidence

聴きながら、すべての言葉を目で追えます

Making Rational Choices: Risk, Reward, and Human Decision-Making

Signal Detection: Balancing False Alarms and Missed Opportunities

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』をもっと深く楽しむ

The Rationality Challenge: Overcoming Biases in a Post-Truth Era

Why Rationality Matters: The Stakes for Our Future

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』を最後まで読み終えました

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の主要テーマ

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の名言

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の登場人物

著者について

21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩の要約をダウンロード

他のユーザーのお気に入り

この本に関するよくある質問

What is Rationality: What It Is, Why It Seems Scarce, Why It Matters about?

Who should read Rationality by Steven Pinker?

Is Rationality worth reading in 2025?

What are the key concepts in Rationality?

もっと見る

1,000,000+ curious minds.

1,000,000+ curious minds.

1冊の本。さまざまな聴き方。

The Paradox of Our Time: Why Rationality Matters Now More Than Ever

The Rational Animal: Our Cognitive Achievements and Limitations

聴きながら、すべての言葉を目で追えます

Rationality's Image Problem: The Case for Reason

The Tools of Logic: Formal Rules and Human Reasoning

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』をもっと深く楽しむ

Probability and Randomness: Navigating an Uncertain World

Bayesian Reasoning: Updating Beliefs with Evidence

聴きながら、すべての言葉を目で追えます

Making Rational Choices: Risk, Reward, and Human Decision-Making

Signal Detection: Balancing False Alarms and Missed Opportunities

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』をもっと深く楽しむ

The Rationality Challenge: Overcoming Biases in a Post-Truth Era

Why Rationality Matters: The Stakes for Our Future

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』を最後まで読み終えました

他のユーザーのお気に入り

もっと見る

『21世紀の啓蒙（下） ――理性の力、科学、ヒューマニズム、進歩』の概要