The Skeptics' Guide to the Universe: How to Know What's Really Real in a World Increasingly Full of Fake

by Steven Novella

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

Skeptics combine knowledge of science, philosophy, human psychology, and all the flaws and biases of human thinking to evaluate all claims and beliefs, especially their own.

The truth may be puzzling. It may take some work to grapple with. It may be counterintuitive. It may contradict deeply held prejudices. It may not be consonant with what we desperately want to be true. But our preferences do not determine what’s true. —Carl Sagan

We are emotional, semi-rational creatures, plagued with a host of biases, mental shortcuts, and errors in thinking.

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, and scientific skeptics therefore rigorously and openly apply the methods of science and reason to all empirical claims, especially their own.

A scientific skeptic provisionally accepts a claim only in proportion to its support from valid logic and a fair and thorough assessment of available evidence. A skeptic also studies the pitfalls of human reason and the mechanisms of deception so as to avoid being deceived by others or themselves. Skepticism values method over any particular conclusion.

Cognitive psychology tells us that the unaided human mind is vulnerable to many fallacies and illusions because of its reliance on its memory for vivid anecdotes rather than systematic statistics. —Steven Pinker

Memories are constructed from imperfect perceptions filtered through our beliefs and biases, and then over time they morph and merge.

Our memories serve more to support our beliefs than to inform them. In a way, they are an evolving story we tell ourselves.

We tend to think that vividness and confidence predict accuracy, but they don’t.

Whenever you find yourself saying, “I clearly remember…” stop! No, you don’t. You have a constructed memory that is likely fused, contaminated, confabulated, personalized, and distorted. And each time you recall that memory you reconstruct it, changing it further.

We’re a bit freaked out by really good optical illusions because they force us to directly confront a reality we tend to ignore as we go through our daily lives: What we think we see is not objective; it is a process of our brains, and that process can be fooled.

The bottom line is this: Your real-time perceptions are not a passive recording of the outside world. Rather, they are an active construction of your brain. This means that there is an imperfect relationship between outside reality and the model of that reality crafted by your brain. Obviously, the model works well enough for us to interact with that reality, and that’s actually the idea. Constructed perception is not optimized for accuracy but rather for functionality.

Essentially, if your visual association cortex thinks you are looking at an elephant, it communicates back to the primary visual cortex and says, “Hey, make that look even more like an elephant.” It changes what you actually see, not just how you interpret it. This all happens automatically, outside of your awareness.

Our brains favor continuity and internal consistency over accuracy, so all these streams are compared in real time and further adjustments made so they all fit together nicely. In a way, our brains are constructing a narrative about what is happening, and making that narrative make sense to us.

As an example of how our brains compare different sensory streams and then tweak them, consider something known as the McGurk effect.

It might seem like these sensations are inevitable consequences of the obvious fact that you are your body. This isn’t true, however. All of those bodily sensations are active constructions by the brain, requiring specific circuits dedicated to that purpose.

There is also a module in the brain called the ownership module. This module is part of a circuit that includes somatic information and also emotional processing. Essentially you feel as if your arm is your arm—it belongs to your body and is part of you. Related to this are circuits that make you feel as if you control the various parts of your body. These circuits compare information about your intention to move to visual and feeling sensation about your actual movements. When your movements match your intentions, your brain creates the sensation that you control your body. If this circuit is interrupted, however, the result is something called alien hand syndrome.

Well, just as with memory, be wary of saying, “I know what I saw.” Hmm… no, you don’t. You have a constructed memory of a constructed perception based on filtered partial sensation and altered by your knowledge and expectations. Psychologists have recognized some specific and dramatic manifestations of the limits of human perception.

who scored lower on a test of working memory.

half the audience noticed anything. The author concluded that “real” reports

Pareidolia refers to the process of perceiving an image in random noise, such as seeing a face in the craters and maria of the moon.

The technical term for the more general phenomenon of seeing patterns where they do not exist is apophenia, the tendency to see illusory patterns in noisy data. The information doesn’t even have to be sensory; the pattern can be in numbers or in events. (In this way conspiracy theories can result from apophenia—seeing a nefarious pattern in random or disconnected incidents.)

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.

Hypnagogia is a neurological phenomenon in which the dreaming and waking states are fused, producing unusual experiences often mistaken for paranormal ones.

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.

If someone is able to show me that what I think or do is not right, I will happily change, for I seek the truth, by which no one was ever truly harmed. It is the person who continues in his self-deception and ignorance who is harmed. —Marcus Aurelius

The Dunning-Kruger effect describes the inability to evaluate one’s own competency, leading to a general tendency to overestimate one’s abilities.

The greatest enemy of knowledge is not ignorance—it is the illusion of knowledge. —Daniel J. Boorstin

The core of the effect, however, seems to be what Dunning describes: Ignorance carries with it the inability to accurately assess one’s own ignorance.

An ignorant mind is precisely not a spotless, empty vessel, but one that’s filled with the clutter of irrelevant or misleading life experiences, theories, facts, intuitions, strategies, algorithms, heuristics, metaphors, and hunches that regrettably have the look and feel of useful and accurate knowledge.

Motivated reasoning is the biased process we use to defend a position, ideology, or belief that we hold with emotional investment.

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.

Non Sequitur From Latin, this term translates to “it doesn’t follow,” and it 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.

Ad Hominem An ad hominem argument is one that attempts to counter another’s claims or conclusions by attacking the person rather than by addressing the argument itself.

A well-known form of this, which has its own name—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.

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.”

Torture the data, and it will confess to anything. —Ronald Coase

The history of science, like the history of all human ideas, is a history of irresponsible dreams, of obstinacy, and of error. But science is one of the very few human activities—perhaps the only one—in which errors are systematically criticized and fairly often, in time, corrected. —Karl Popper

Features of Pseudoscience

1) Working Backward from Conclusions 2) Hostility Toward Scientific Criticism, Claims of Persecution 3) Making a Virtue out of Ignorance 4) Reliance upon Weak Forms of Evidence While Dismissing More Rigorous Evidence 5) Cherry-Picking Data 6) Fundamental Principles Are Often Based upon a Single Case 7) Failure to Engage with the Scientific Community 8) Claims Often Promise Easy and Simplistic Solutions to Complex Problems or Questions 9) Utilizing Scientific-Sounding but Ultimately Meaningless Language 10) Lack of Humility—Making Bold Claims on Flimsy Evidence 11) Claiming to Be Years or Decades Ahead of the Curve 12) Attempts to Shift the Burden of Proof Away from Themselves 13) Rendering Claims Non-Falsifiable 14) Violating Occam’s Razor and Failing to Fairly Consider All Competing Hypotheses 15) Failure to Challenge Core Assumptions

This lesson reflects a more general observation credited to George Santayana: “Those who do not learn history are doomed to repeat it.”

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.