Common sense used to dictate that men and women should only come together for breakfast and dinner.

According to Victorian historian Kaythrn Hughes, people in the early 19th Century thought the outside world was dangerous and unclean and morally dubious and thus no place for a virtuous, fragile woman. The home was a paradise, a place for civility, where perfect angelic ladies could, in her words, “counterbalance the moral taint of the public sphere.”

Hypothetical situations involving dragons, robots, spaceships, and vampires have all been used to prove and disprove arguments.

Statements about things that do not exist can still be true, and can be useful thinking tools for exploring philosophical, logical, sociological, and scientific concepts.

The problem is that sometimes those same arguments accidentally require those fictional concepts to be real in order to support their conclusions, and that’s when you commit the existential fallacy.

Here is a logic puzzle created by psychologists Daniel Kahneman and Amos Tversky.

“Linda is single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with the issue of discrimination and social justice, and also participated in demonstrations. Which of the following is more probable: Linda is a bank teller or Linda is a bank teller AND is active in the feminist movement?”

In studies, when asked this question, more than 80 percent of people chose number two. Most people said it was more probably that Linda is a bank teller AND active in the feminist movement, but that’s wrong. Can you tell why?

We often overestimate and overstate just how much we can learn about a claim based on where that claim originated, and that’s the crux of the genetic fallacy, according to the experts in this episode.

The genetic fallacy appears when people trace things back to their sources, and if you traced back to their shared source the ad hominem attack (insulting the source instead of attacking its argument) and the argument from authority (praising the source instead of supporting its argument), you would find the genetic fallacy is the mother of both kinds of faulty reasoning.

You might be in danger of serially committing the genetic fallacy if your first instinct is to ask where attitude-inconsistent comes from once you feel the twinge of fear that appears after a belief is threatened.

Without realizing it, you sometimes apply a double standard to the things you love, believe, and consider crucial to your identity.

If you do this while arguing, it is sometimes called special pleading. You search for exemptions and excuses for why a rule or a description or a definition does not apply to something that you hold dear while still applying those standards to everything else.

If you believe something is bad because it is…bad, or that something is good because, well, it’s good, you probably wouldn’t use that kind of reasoning in an argument – yet, sometimes, without realizing it, that’s exactly what you do.

If you think eating shrimp is immoral, you might defend that viewpoint by saying, “People shouldn’t eat shrimp because eating shrimp is unethical.” Ok, yes, got it, but you just looped back around without defending your original assertion.  We are going to need to hear some justification for your views on morality.

Likewise, when explaining why something is true, we often unwittingly provide false clarity. For instance, you might read something like, “Human beings enjoy looking at each other’s butts because we evolved to appreciate healthy backsides.” Broken down, this is just a rephrasing of, “People like butts because people like butts.” There’s no answer here, no cause to the effect, no argument for or against, no explanation for why the observable is observable.

So why do we do this, and why don’t we notice it when other people do it?

You don’t treat all of your beliefs equally.

For some, you see them as either true or false, correct or incorrect. For others, you see them as probabilities, chances – odds. In one world, you live in certainty, in the other, uncertainty.

In this episode we explore why you gladly update some beliefs yet refuse to update others.