John Oliver's February 24, 2019 edition of Last Week Tonight was an exposé of the popularity of psychics on American daytime television. He reported that 4 out of 10 people believe that psychics are effective and that billions of dollars are spent yearly by people desperate to have psychics help them with their problems.

What is the psychology of people's to psychics who use paranormal methods such as to answer people's questions? What is the appropriate logic for evaluating such methods?

You might be inclined to believe that psychics tell the truth. First, they often seem to know uncanny and accurate information about the people in their audiences—for example, that someone has a spouse who died of heart disease. Second, the people who get information from psychics seem to feel better as a result—for example, when they are told that a missing child is still alive. Third, the psychics appear on national television with famous hosts who have some credibility.

Oliver pointed out that there are alternative interpretations of all of these observations. Psychics use two main methods to appear to be accurate and informative about people's problems.

The most common is cold calling, which is throwing up big questions designed to elicit information—for example, by asking whether anyone in a large audience has a husband named John who had a heart attack. People are eager to be informed about their loved ones and find solace, so they quickly pick up on tiny pieces of information achieved only by fake questions and statements.

The other method commonly used by psychics is hot calling, which means getting information in advance about people they know they will meet, through sources such as Facebook. Deceptions through cold and hot calling explain why psychics seem to be accurate and insightful.

When people are thrilled to get information about loved ones from psychics, they are often succumbing to the kind of mental error that psychologists call motivated reasoning. People are inclined to accept beliefs on the basis of personal —what they want to believe—rather than on reliable evidence.

is not just wishful thinking; it involves a more subtle process of recruiting information from and other sources in ways that support what one wants to hear. from the loss of a loved one is a horrible experience, so is not surprising that people will be highly motivated to get information that will make them feel better. So the fact that people think that psychics make them feel better is no evidence concerning the truth of what the psychics say, because it reflects motivated inference rather than more reliable reasoning.

People may also be taken in by other kinds of thinking errors well known to psychologists, such as clustering illusion, bandwagon effects, and confirmation bias. So the acceptance of psychics’ claims by vulnerable people is better explained by thinking errors than by the truth of the psychics' claims.

The third reason why television psychics might be taken to be credible is the reputation of the shows' hosts. But many of those hosts are primarily interested in getting high ratings and rewards rather than conveying valid information. The hosts are highly motivated to select guests based on entertainment value rather than on independent credibility, so the fact that psychics are seen on TV is no reason to suppose that they are speaking the truth.

The appropriate logic for evaluating the claims of psychics is what philosophers call inference to the best explanation, which I discussed in my last post. It would be okay to believe in psychics if the best explanation of what they do is that they have a real gift for communicating with the dead, foreseeing the future, or performing other acts of extrasensory perception. Counting against this conclusion is the alternative hypothesis that psychics are just frauds, using methods like cold calling and hot calling to trick people into thinking that they have special powers. Psychics have their own motivations for pretending that they have special powers including the pursuit of fame and fortune.

Another reason for doubting claims about extrasensory perception is that there are no known physical mechanisms by which people could communicate with the dead or foresee the future. More strongly, these alleged phenomena are contrary to everything that is known about the way information can be passed through physical processes. People have looked for good scientific evidence for paranormal phenomena since at least the 19th century, but apparent successes can be explained by incompetence or fraud or error rather than by the actual occurrence of paranormal phenomena.

In a 2012 post, I offered the following profile of how pseudoscience differs from science:

Science explains using mechanisms, whereas pseudoscience lacks mechanistic explanations. Science uses correlation thinking, which applies statistical methods to find patterns in nature, whereas pseudoscience uses dogmatic assertions, or resemblance thinking, which infers that things are causally related merely because they are similar. Practitioners of science care about evaluating theories in relation to alternative ones, whereas practitioners of pseudoscience are oblivious to alternative theories. Science uses simple theories that have broad explanatory power, whereas pseudoscience uses theories that require many extra hypotheses for particular explanations. Science progresses over time by developing new theories that explain newly discovered facts, where pseudoscience is stagnant in doctrine and applications.

Parapsychology as used by psychics fits this pseudoscience profile and accordingly should be dismissed as a source of reliable knowledge.