*Some editing and language added by Barbara A. Drescher

Some people promote theories and treatments that they claim to be scientific, but are not. On this website, we often refer to such dubious claims as “woo” or pseudoscience. These often troublesome theories and treatments are widely advertised on the internet, on TV, and in the psychology or self-help sections of commercial book stores. But because some material in these venues is legitimate, it is important to know how to distinguish science from pseudoscience.

Here we provide a useful toolkit which can be used to identify pseudoscience. The following warning signs are just a rough guide and should be used with some care, because the distinction between science and pseudoscience is rarely clear-cut. Nevertheless, the more warning signs, the more suspicious of a claim you should be.

It cannot be tested.

Pseudoscience is often either impossible to test or excuses are made which keep it from being tested. In some cases, when evidence does not support the claim, instead of abandoning their ideas, pseudoscientists add conditions to their theories or explain away the evidence so that it is impossible to test the claim empirically. For example, a psychic who cannot demonstrate mind reading or other psychic feats under carefully controlled conditions in the laboratory might claim that “the skeptical vibes of experimenters” are blocking his or her psychic powers. Such an excuse makes the claim untestable. In other cases, pseudoscientific theories cannot be tested right from the start.

The basic theory does not change in response to evidence. Genuine science adapts and updates its theories in response to new evidence, especially refuting evidence. In contrast, pseudoscience tends to maintain its initial claims and instead dismisses or ignores counter-evidence.

The claimants avoid peer review or other outside verification. Peer review is the checking of scientific-journal articles by other scientists. Although it is by no means perfect, peer review is an effective, if slow, safeguard against human error. Pseudoscientists tend to avoid close scrutiny. In many cases, their descriptions of procedures and mechanisms are vague and the terms they use are undefined (e.g., “energy”). In other cases they may claim that “orthodox science” conspires against them.

They only look for evidence which confirms their hypothesis. In science, studies are designed to disprove hypotheses, not to confirm them. This is because confirming evidence cannot tell us if the hypothesis is always true or if we have simply not seen a case in which it is false. For example, we could test the hypothesis that all birds fly by dropping birds from a bridge. We would confirm our hypothesis many times over, but we would not discover that it was wrong unless we happened to drop a chicken, penguin, or ostrich. Scientists look for evidence that their theories are false. Pseudoscientists, however, often look only for evidence which supports their beliefs.

The claimant insists that their theory is accurate because it has not been proven wrong.

Pseudoscientists typically say that it up to critics to disprove their claims, and until they do they should hold firmly to their beliefs. However, the burden of proof is on those making the claim.

The claim defies what established science has told us about the world. Pseudoscientists often claim to have discovered a completely new way of looking at the world, one which requires existing scientific knowledge to be tossed out. For example, “psychic surgeons” claim to remove tumors from a patient’s abdomen without cutting the skin. This is considered an extraordinary claim as it defies the laws of nature as we know them. Such claims require extraordinary evidence.

The claimants attempt to persuade using anecdotes. Pseudoscientists tend to rely on evidence that is testimonial – engaging and vivid personal stories. These stories are often touching and persuasive. Although such testimonies may be useful starting points in the early stages of scientific study, they rarely provide enough evidence to accept a claim. That’s because they are often difficult to verify, unrepresentative of people’s experiences, and open to alternative explanations that pseudoscientists haven’t considered.

The claimants use confusing and inappropriate scientific-sounding jargon to persuade. Pseudoscientists sometimes use jargon which hides the lack of substance in their claims. Scientific or highly technical words are used to impress the reader and make it look like science. Technical or scientific terms are often used out of context. For example, the claim that a product regulates the flow of ions in the body is a misuse of the term “ion”, which refers to states of a molecule, not something that flows in the body.

The claim has no limits. In science, theories are specific and treatments have limits. In contrast, pseudoscientists often claim that their theory or treatment applies to just about everything. For example, sham treatments for ADHD also claim to treat or even cure autism, learning disabilities, and other behavioral disorders even though these disorders are completely different in nature and have different causes.