Compendium 12 — Rationality: What It Is, Why It Seems Scarce, Why It Matters

“Each of us has a motive to prefer our truth, but together we’re better off with the truth.” — Steven Pinker

📖 Brief Overview

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In Rationality: What It Is, Why It Seems Scarce, Why It Matters, Steven Pinker explores the concept of rationality, an inherent quality in humans, yet often underutilized in the decision-making process. Pinker delves into the psychology behind human reasoning, emphasizing the importance of rational thinking in modern society characterized by misinformation and irrational narratives.

Through a multidisciplinary approach involving cognitive science, behavioral economics, and philosophy, the book unveils how humans can harness rationality to navigate the complex world of today. It discusses various cognitive tools like logic, probability, correlation and causation, and critical thinking, which aid in rational thought processes.

The book not only highlights the scarcity of rational thinking in public discourse but also offers a path to enhancing individual and collective rationality. It is a deep dive into the nuances of human cognition and a call to foster a society grounded in reason and critical analysis. It's a timely piece that stands against the backdrop of a world grappling with misinformation and divisive narratives, urging individuals to embrace rationality as a guiding force in a polarized society.

🏆 Main Takeaways

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Understanding Rationality: The Interplay of Knowledge, Goals, and Self-Defeating Arguments

1. Defining Rationality: Rationality is the ability to use knowledge to achieve goals. It involves having justified true beliefs that serve a purpose, whether that's understanding truth (theoretical reason) or taking action (practical reason).

2. Knowledge and Justification: Rationality depends on knowledge, which is defined as justified true belief. Beliefs must be based on evidence, observation, or inference from other true beliefs to be considered rational.

3. Goals and Purpose: Rational agents have specific goals or objectives in mind when applying their rationality. Whether it's seeking truth or making decisions, rationality is always directed towards achieving something.

4. Self-Defeating Arguments: Arguing against reason inherently contradicts itself. If you claim that rationality is unnecessary or that everything is subjective or relative, these claims themselves rely on rationality. This leads to logical paradoxes, highlighting the fundamental role of reason in discourse.

5. Post-Truth Era Fallacy: The notion of a "post-truth era" is self-contradictory. If it were true, it would assert a truth about the era, negating its own premise. This demonstrates that even in discussions about truth and rationality, a rational framework is essential.

“Man is a rational animal. So at least we have been told. Throughout a long life I have searched diligently for evidence in favor of this statement. So far, I have not had the good fortune to come across it.” — Bertrand Russell

Quantifying Uncertainty: The Challenge of Conjunction in Probability Estimations

1. Quantifying Future Events: Assigning probabilities to uncertain future events is essential for various fields, including policy-making, investment, and risk management.

2. Conjunction Rule: The conjunction rule in probability states that the probability of two events occurring together (A and B) must be equal to or less than the probability of either event occurring alone (A or B).

3. Examples of Violating Conjunction Rule:

   • People often thought it was more likely for Putin's wife to become president of Russia (a conjunction of events) than for a woman to become president (either event alone).

   • They believed that strikes would force Maduro to resign (conjunction) was more likely than Maduro resigning (either event alone).

   • They considered Saudi Arabia developing a nuclear weapon in response to Iran (conjunction) more likely than Saudi Arabia developing a nuclear weapon (either event alone).

   • People thought a pandemic caused by Chinese bats (conjunction) was more likely than a pandemic (either event alone).

4. Consequences of Violating the Rule: Violating the conjunction rule can lead to biased judgments and flawed decision-making, as it ignores the fundamental principles of probability.

5. Conjunction of Events: In pairs of world events where the second scenario is a conjunction of events, one of which is the event in the first scenario, the second scenario should logically have a smaller chance of happening. For instance, "Iran tests a nuclear weapon and Saudi Arabia develops a nuclear weapon" is a conjunction that includes "Saudi Arabia develops a nuclear weapon," and this should have a smaller likelihood because there are multiple scenarios in which Saudi Arabia might develop a nuclear weapon.

6. Imaginability and Probability: People's intuitive probability judgments are often influenced by how easily they can visualize or imagine an event. Conjunctions of events tend to be more vivid and story-like, making them easier to imagine, which leads individuals to assign them a higher likelihood.

7. Conjunction Fallacy: This cognitive bias, described by Tversky and Kahneman, occurs when people perceive a conjunction of events as more probable than one of its individual elements, which violates the basic principles of probability theory.

“Extraordinary claims require extraordinary evidence.” — Carl Sagan