50 Concepts from The Skeptics' Guide to the Universe (Book Summary)

This is a book summary of The Skeptics’ Guide to the Universe: How to Know What’s Really Real in a World Increasingly Full of Fake by Dr. Steven Novella (Amazon).

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Quick Housekeeping:

All content in quotation marks is from the author unless otherwise stated.
All content is organized into my own themes (not the author’s chapters).
Emphasis has been added in bold for readability/skimmability.

Book Summary Contents: Click a link here to jump to a section below

About the Book
What is Scientific Skepticism?
50 Skeptic Concepts

Skeptics Guide to the Universe Book Summary

**50 Skeptic Concepts from The Skeptics’ Guide to the Universe by Steven Novella (Book Summary)**

About the book The Skeptics’ Guide to the Universe

“This book is meant to be one giant inoculation against bad science, deception, and faulty thinking.”

“If you’re reading this guide, you likely want to think for yourself and be purged of misinformation, sloppy thinking, and false beliefs.”
“Ultimately this is a journey of self-discovery, and hopefully this book will serve as a guide on that journey. In these pages you will learn about the many ways in which your brain fails, its tendency to prefer nice clean and reassuring stories, the absolute mess that is your memory, and all the preprogrammed biases in your thinking.”
“You will also learn about the many ways in which society fails, the imperfections in the institutions of science, learning, and journalism. It’s intimidating to realize that we live in a world overflowing with misinformation, bias, myths, deception, and flawed knowledge.”
“The skeptical, critical thinking, and scientific principles outlined in this book are like the rungs of a long ladder that humanity has used to climb laboriously out of the swamp of superstition, bias, hubris, and magical belief. We tend to look back now at medieval beliefs and congratulate ourselves for being born in a later age. But not every individual or even every institution has followed our best thinkers out of the muck. We all need to climb the ladder for ourselves.”
“It is especially tragic when we have the science—we did the research, did the hard work, and have real solutions for people who need them. But stubbornness and ideology can’t help but get in the way.”

The book is organized into three main categories:

Neuropsychological Humility: “This category includes knowledge of all the ways in which your brain function is limited or flawed … Before hypothesizing about spirits, new forces, or supernatural abilities, consider that—just maybe—your brain (like the brain of every other human on the planet) has some quirks and foibles. That is the meaning of neuropsychological humility.”
Metacognition: “The second category of skeptical ‘gear’ is called metacognition—thinking about thinking. Metacognition is an exploration of all the ways in which your thinking is biased … Part of skeptical philosophy, metacognition, and critical thinking is the recognition that we all suffer from powerful and subtle cognitive biases. We have to both recognize them and make a conscious effort to work against them, realizing that this is an endless process. Part of the way to do this is to systematically doubt ourselves.”
Science & Pseudoscience: “The third type of skeptical equipment has to do with science—how it works, the nature of pseudoscience and denialism, and how science can go wrong … All the pseudosciences we confront today have their roots in the past. The work of scientists and skeptics in previous decades can act like a vaccine, allowing us to mount a more rapid and robust response to fraud and quackery today.”

What is Scientific Skepticism?

“This is the essence of skepticism: How do we know what to believe and what to doubt?”

“Scientific skepticism, a term first popularized by Carl Sagan, is an overall approach to knowledge that prefers beliefs and conclusions that are reliable and valid to ones that are comforting or convenient.”
“Skepticism values method over any particular conclusion.”
“Once you begin to ask questions like ‘How do we actually know anything?’ our beliefs start to fall one by one.”
“Skepticism is largely a systematic effort in metacognition, which means understanding how we think and avoiding common mental pitfalls.”
“Where scientific skepticism gets involved is when people make claims, have a pretense to knowledge, or state something as a fact or as if it’s a valid conclusion of logic or science.”
“Skepticism goes beyond cynicism. While it may start with doubt, that’s the beginning, not the end. There isn’t any definitive or ultimate knowledge (no Truth with a capital T), but we can grind out knowledge about the world that is sufficiently reliable for us to treat it as provisionally true and act upon it.”
“Being a skeptic means doubting, but philosophical skepticism is distinct from scientific skepticism and is not what we advocate. Philosophical skepticism is essentially a position of permanent doubt: Can we actually know anything? And what is the nature of knowledge itself?”
“That’s why ‘scientific’ skeptics are not philosophical skeptics, professing that no knowledge is possible. We are also not cynics, who doubt as a social posture or just have a generally negative attitude about humanity. We are not contrarians who reflexively oppose all mainstream opinions.”

50 Skeptic Concepts from The Skeptics’ Guide to the Universe

1. Confabulation:

“Put simply, we make shit up. This is a completely automatic and subconscious process. Again, our brains want to construct a continuous and consistent memory, so if there are any missing pieces it just makes them up to fill in the gaps.”

2. False Memory Syndrome:

“The construction of entirely fake memories. This is accomplished through guided imagery, hypnosis, suggestion, and group pressure.”

3. Attentional (or Inattentional) Blindness & Change Blindness:

Attentional (or Inattentional) Blindness: “We don’t see what we are not paying attention to, even if it happens right in front of our eyes.”
Change Blindness: “Reflects our inability to notice changes in detail. We do tend to notice changes that occur in front of us, but not when they occur outside our direct view.”

4. Baader-Meinhof Phenomenon:

“Once you stumble upon an obscure word or fact, you encounter it again and again, seemingly against the odds. This is part simple coincidence but also part perception bias. You’ve likely encountered the word or fact before, but you just didn’t notice it.”

5. Pareidolia:

“Pareidolia refers to the process of perceiving an image in random noise (the perception of familiar yet meaningless patterns in random stimuli or noise), such as seeing a face in the craters and maria of the moon.”

6. Hyperactive Agency Detection:

“Hyperactive agency detection is the tendency to interpret events as if they were the deliberate intent of a conscious agent rather than the product of natural forces or unguided chaotic events.”

7. Hypnagogia:

“Hypnagogia is a neurological phenomenon in which the dreaming and waking states are fused, producing unusual experiences often mistaken for paranormal ones … Hypnagogia is a neurological phenomenon that can occur when a person is waking up (hypnopompic) or going to sleep (hypnagogic). It’s an in-between state where the person is neither fully awake nor fully asleep. In this state, very realistic images and sounds can be experienced.”

8. Ideomotor Effect:

“The ideomotor effect is an involuntary subconscious subtle muscle movement driven by expectation, which creates the illusion that the movement is due to an external force … The ideomotor effect describes the subtle, unconscious muscular movements people make that result in the moving of objects.”

9. Dunning-Kruger Effect:

“The Dunning-Kruger effect describes the inability to evaluate one’s own competency, leading to a general tendency to overestimate one’s abilities … The most competent individuals tend to underestimate their relative ability a little, but most people (the bottom 75 percent) increasingly overestimate their ability, and everyone thinks they’re above average.”

10. Clever Hans Effect:

“The Clever Hans effect refers to an unconscious nonverbal communication of information from a researcher or agent to an animal or other subject. This unconscious communication creates the illusion of a cognitive or supernatural ability.”

11. Hawthorne Effect (Observer Effect):

“The Hawthorne or observer effect refers to the fact that simply observing something may alter its behavior, thereby creating an artifact that leads to an incorrect conclusion.”

12. Motivated Reasoning & Cognitive Dissonance:

Motivated Reasoning: “Motivated reasoning is the biased process we use to defend a position, ideology, or belief that we hold with emotional investment … We all have narratives by which we understand the world and our place in it. Some narratives are critical to our sense of identity. Preferred narratives support our worldview, our membership in a group, or our self-perception as a good and valuable person. We have narratives and beliefs that serve our basic psychological needs, such as the need for a sense of control. When those beliefs are challenged, we don’t take a rational and detached approach. We dig in our heels and engage in what is called motivated reasoning. We defend the core beliefs at all costs, shredding logic, discarding inconvenient facts, making up facts as necessary, cherry-picking only the facts we like, engaging in magical thinking, and using subjective judgments as necessary without any consideration for internal consistency. Collectively, these processes constitute motivated reasoning.”
Cognitive Dissonance: “Motivated reasoning is triggered by what psychologists call cognitive dissonance. Cognitive dissonance theory was first proposed by Leon Festinger in 1957. He suggested that psychological discomfort results when we are presented with two pieces of information that conflict with each other. We hold a belief, and now we have information that contradicts that belief.”

13. Principle of Charity:

“Give the other the benefit of the doubt—take the best interpretation of their position possible and deconstruct that.”

14. Non Sequitur:

“‘It doesn’t follow’ … refers to an argument in which the conclusion does not necessarily follow from the premises. In other words, a logical connection is implied where none exists.”

15. Reductio ad Absurdum:

“‘Reduction to the absurd’ … It follows the form that if the premises are assumed to be true, logic necessarily leads to an absurd (false) conclusion, and therefore one or more premises must be false. The term is now often used to refer to the abuse of this style of argument, when the logic is deliberately stretched in order to force an absurd conclusion.”

16. Tautology (Begging the Question):

“An argument that utilizes circular reasoning, which means that the conclusion is also its own premise. The structure of such arguments is A = B therefore A = B, although the premise and conclusion might be formulated differently so the tautology is not immediately apparent … This fallacy is often called ‘begging the question,’ meaning that the premise assumes the conclusion, or that an argument assumes its initial point.”

17. Post Hoc Ergo Propter Hoc:

“‘After this, therefore because of this’ … follows the basic format of A preceded B, therefore A caused B, assuming cause and effect for two events just because they are temporally related.”

18. Confusing Correlation with Causation, Data Mining, & Anomaly Hunting:

Confusing Correlation with Causation: “Often used to give a statistical correlation a causal interpretation … In essence there are always four possible interpretations of any apparent correlation. The first is that the correlation is not causal at all. The second is that A causes B. The third is that B causes A. The fourth is that A and B are both caused by another variable, C. It’s helpful to go through all such possibilities before concluding that any one causal pattern is true.”
Data Mining: “Data mining is the process of sifting through large sets of data looking for any possible correlation, many of which will occur by chance. While this is a legitimate method for generating hypotheses, such data are not confirmatory and the method is easily abused … The problem of data mining is both common and often subtle and missed. It’s rooted in both the nature of human brain function and a common logical fallacy. The former is that of pattern recognition and the latter the fallacy of confusing correlation with causation.”
Anomaly Hunting: “The fallacy of anomaly hunting comes from looking for anything unusual, assuming any apparent anomaly is unexplainable, and then concluding that it is evidence for one’s pet theory.”

19. Special Pleading (or Ad Hoc Reasoning):

“The arbitrary introduction of new elements into an argument in order to jerry-rig that argument so it appears valid.”

20. Tu Quoque:

“‘You too’ … An attempt to justify wrong action because someone else does the same thing.”

21. Ad Hominem:

“Attempts to counter another’s claims or conclusions by attacking the person rather than by addressing the argument itself (e.g. Godwin’s Law or the reductio ad Hitlerum—refers to an attempt at poisoning the well by drawing an analogy between another’s position and Hitler or the Nazis.)”

22. Ad Ignorantiam & Confusing Currently Unexplained with Unexplainable:

Ad Ignorantiam: “The argument from ignorance basically states that a specific belief is true because we don’t know that it isn’t true (e.g. arguments from ignorance are often referred to as ‘god of the gaps’ arguments, because God is offered as the explanation for any current gap in our knowledge.)”
Confusing Currently Unexplained with Unexplainable: “Because we don’t currently have an adequate explanation for a phenomenon does not mean that it’s forever unexplainable or that it therefore defies the laws of nature or requires a paranormal explanation. This is often tied to the argument from ignorance, assuming that our current ignorance will never be filled in by knowledge.”

23. Argument from Authority & Appeal to Antiquity:

Argument from Authority: “Often this argument is implied by emphasizing the many years of experience of the individual making a specific claim, or the number of formal degrees they hold … Any time you rely on the source of an argument or position rather than facts and logic, that may become an argument from authority.”
Appeal to Antiquity: “The appeal to antiquity is a special form of the appeal-to-authority fallacy. In this case the alleged authority is the assumption of ancient wisdom, or the notion that an idea that has stood the test of time must be valid … The assumption is that if people have been doing something for so long, there must be something to it. Typically, those employing this fallacious argument will try to rescue it by arguing that it is valid because antiquity implies that the method has stood the test of time. This argument, however, isn’t valid, because it contains a major unstated premise that isn’t true—namely, that time will test such modalities as a matter of course. History has shown this is a false assumption.”

24. Argument from Final Outcome & Argument from Final Consequences:

Argument from Final Outcome: “Such arguments (also called teleological) are based on a reversal of cause and effect, because they argue that something is caused by the ultimate effect that it has or the purpose that it serves.”
Argument from Final Consequences: “Evolution is wrong because if it were true society would suffer. This feature also often provides a clue as to the true motivation of the denial. The science is secondary: It’s the moral hazard they’re truly concerned about. This is an inherently flawed strategy. If you truly wish to advocate for a particular moral or ethical position, the worst thing you can do is tie that position to a false scientific conclusion. Doing so allows opponents to attack your moral position by attacking the pseudoscience to which you have anchored it. You are far better off acknowledging legitimate science and advocating for your moral position on moral grounds.”

25. False Continuum, False Dichotomy, & False Analogy:

False Continuum: “The idea that because there is no definitive demarcation line between two extremes, the distinction between the extremes is therefore not real or meaningful.”
False Dichotomy: “Arbitrarily reducing a set of many possibilities to only two.”
False Analogy: “Assuming that because two or more things are similar in one way, then they are also similar in some other way, ignoring any important distinctions between the two.”

26. Naturalistic Fallacy & Appeal to Nature:

Naturalistic Fallacy: “The is/ought problem, confusing what is true with what ought to be true. This is not to be confused with the appeal-to-nature fallacy, which posits that being natural is in itself a virtue and anything natural is inherently superior to anything artificial.”
Appeal to Nature: “The appeal to nature is a logical fallacy based upon the unwarranted assumption that things that are natural are inherently superior to things that are manufactured. Additionally, it relies upon a vague definition of ‘natural’ … It is distinct from the naturalistic fallacy, which refers mainly to the idea that whatever is in nature ought to be (the ‘is/ought’ problem) as outlined by David Hume … The appeal-to-nature fallacy is related to the naturalistic fallacy as a special case—some things that are good are natural, so all things natural must be good. The flip side of the appeal-to-nature coin is that anything that is ‘unnatural’ is inherently tainted to some degree.”

27. Genetic Fallacy:

“Arguing against something because of where it came from, rather than considering whether or not it is valid in its current form.”

28. Nirvana Fallacy:

“That ‘the perfect is the enemy of the good.’ Essentially this style of argument starts with the premise that something is not perfect and concludes that it is therefore worthless.”

29. Fallacy of Relative Privation:

“The notion that what you are doing is not valuable because there is a more important issue out there that needs attention … ‘Don’t bother doing anything until we cure childhood cancer,’ for example.”)

30. No True Scotsman:

“The argument is made that all Scotsmen are brave, and when a counterexample of a cowardly Scotsman is provided, the original claim is defended by saying, ‘Well then, he’s no true Scotsman.’ In essence this fallacy consists of making an argument true by arbitrarily altering the definition of a key term so that the argument is true by definition. It can therefore be considered a special case of the circular reasoning fallacy.”

31. Slippery Slope:

“The argument that a position is not consistent or tenable because accepting the position means that the extreme of the position must also be accepted.”

32. Straw Man:

“Argument in which you construct a weak version of someone else’s position so that it’s an easier target for you to knock down.”

33. Texas Sharpshooter Fallacy:

“A target shooter claims that he can always hit the bull’s-eye. He aims at the side of a barn, shoots a hole in the wood, then goes up and draws a target around the hole he just made, giving himself a bull’s-eye. What this analogy refers to is when someone chooses the criteria for success or failure after they know the outcome. It becomes a form of post hoc reasoning, deciding that a certain piece of evidence is evidence for the conclusion you desire, but you decide that only after you know what the evidence is.”

34. Gambler’s Fallacy:

“If you flip a fair coin heads five times in a row, most people will feel tails is now due. The bias is the thinking that past events influence future events, even when there is no causal connection. Since each coin flip is independent, it does not matter what happened before.”

35. Fallacy Fallacy:

“Concluding that a claim must be wrong because one argument proposed for it is not valid.”

36. Confirmation Bias:

“Confirmation bias is the tendency of individuals to seek out or interpret new information as support for previously held notions or beliefs, even when such interpretations don’t hold up to statistical scrutiny … Confirmation bias is a tendency to notice, accept, and remember information that appears to support an existing belief and to ignore, distort, explain away, or forget information that seems to contradict an existing belief. This process works undetected in the background of our minds to create the powerful illusion that the facts support our beliefs.”

37. Desirability Bias:

“We are biased toward information that supports what we want to be true, even if we don’t already believe it.”

38. Framing Bias:

“Your thinking about something can be dramatically affected simply by how it is presented to you.”

39. In-Group & Out-Group Bias:

“We need to feel we are part of a group where we are liked and accepted. Thus there is an in-group bias—we are biased toward our group, making much more favorable judgments of our in-group than an out-group. Similarly, we are hugely biased toward ourselves. We will give ourselves every benefit of the doubt and interpret our own actions in the most favorable light.”

40. Projection Bias:

“We also tend to assume that other people think like we do, a phenomenon called the projection bias. This is the way we think about and understand what other people are likely thinking. We tend to use our own mind as a template to make predictions about how other people will think and act. So if something bothers us, we assume it bothers other people as well. This is closely related to the consensus bias. We tend to assume that our own opinions are in the majority, that most other people share them.”

41. Hindsight Bias:

“Once we know the outcome of a situation, that knowledge colors our interpretation of what happened and why. We tend to think that whatever happened was inevitable, destined to happen, even if it was a close call.”

42. Unit Bias:

“It derives from a desire to simplify a complex world to make some reasonable first approximations that aren’t always accurate. We tend to focus on one salient feature of an item or thing and use that feature as the one measure of value, quality, or quantity.”

43. Occam’s Razor:

“The principle of Occam’s razor, attributed to William of Ockham (1287–1347), states that when two or more hypotheses are consistent with the available data, then the hypothesis that introduces the fewest new assumptions should be preferred. In the original Latin, ‘Non sunt multiplicanda entia sine necessitate,’ which translates to ‘Entities must not be multiplied without necessity’ … The direct quote from William of Ockham is this: ‘Numquam ponenda est pluralitas sine necessitate’ (Plurality must never be posited without necessity) … Stated another (and more accurate) way, Occam’s razor is the principle that the introduction of new assumptions should be minimized. ‘New assumptions’ shouldn’t be conflated with ‘additional explanations or diagnoses.’ That is the error.”

44. Availability Heuristic:

“The unstated assumption that if we can easily call an example of something to mind, it must therefore be common or important.”

45. Representativeness Heuristic:

“We tend to think that someone or something likely belongs to a category if they have features typical of that category. While there is some truth to this, we overapply the rule and ignore two other critical pieces of information. First is the base rate—how common is that category? If the category is rare, then the probability of someone belonging to that category may still be low, even if they are typical for it. The second is predictive value—a feature may be typical of a category but not specific to it.”

46. Anchoring Heuristic:

“This one is also common in marketing. Let’s say I show you a house and then ask you if you think the house is worth more or less than $100,000. I then ask you what you think the house is worth. I ask another person if they think the same house is worth more or less than $500,000, and then I ask them to guess the price. The person who was ‘anchored’ to the $100,000 reference will guess significantly lower than the person who was anchored to the $500,000 price, even though they’re assessing the same house.”

47. Fundamental Attribution Error:

“The fundamental attribution error (or correspondence bias) is a cognitive bias in which we ascribe other people’s actions to internal factors such as personality while rationalizing our own actions as being the result of external factors beyond our control … We’re quick to conclude we’re the victim of circumstance, and we tend to be acutely aware of external factors that influence our thoughts and behavior. For other people, however, we tend to assume they are driven predominantly by internal factors having to do with their disposition and qualities.”

48. Subjective Validation:

“The tendency to use subjective criteria to validate our prior beliefs.”

49. Cold Reading (Mentalism):

“Cold reading is a collection of mentalism techniques used to create the illusion of having gained specific knowledge about a target through supernatural means. The techniques involve use of vague statements, high-probability guesswork, and feeding back knowledge gained from the subject themselves, while the target makes connections to their own personal experience. Cold reading is used in stage magic for entertainment, but also by a wide variety of less honest practitioners to feign psychic or arcane abilities … Going from vague statements to specific examples when connecting a guess to yourself is a known psychological phenomenon. It was first described by the psychologist Bertram R. Forer in 1949 and is now known as the Forer effect, although it’s also often called the Barnum effect after the famous carnival showman.”

50. Denialism, Moving Goalpost, & Solution Aversion:

Denialism: “Denialism or science denial refers to the motivated denial of accepted science using a series of invalid strategies … Denialism begins with the desire to deny an accepted scientific or historical fact, and therefore, like all pseudosciences, works backward from the desired conclusion … Denialism is a subset of pseudoscience, one that tries to cloak itself in the language of skepticism while eschewing the actual process of scientific skepticism. Denialism exists on a spectrum with skepticism, without a clear demarcation between the two (similar to science and pseudoscience).”
Moving Goalpost: “A method of denial that involves arbitrarily moving the criteria for ‘proof’ or acceptance out of range of whatever evidence currently exists. If new evidence comes to light meeting the prior criteria, the goalpost is pushed back further—keeping it out of range of this new evidence.”
Solution Aversion: “Reject the science because you don’t like the proposed solutions. Again, it’s a better strategy to focus on the solutions rather than deny the science.”

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