How To Spot a Logical Fallacy Part 1

A fallacy is reasoning that is logically incorrect, undermines the logical validity of an argument, or is recognised as unsound. All forms of human communication can contain fallacies.

Because of their variety, fallacies are challenging to classify. They can be classified by their structure (formal fallacies) or content (informal fallacies). There are tons more informal fallacies!

The use of fallacies is common when the speaker’s goal of achieving common agreement is more important to them than utilizing sound reasoning. When fallacies are used, the premise should be recognized as not well-grounded, the conclusion as unproven (but not necessarily false), and the argument as unsound.

We are not going to cover: Propositional fallacies, Quantification fallacies or Formal syllogistic fallacies.

Formal fallacies – an error in the argument’s form. All formal fallacies are types of non sequitur.

Appeal to probability (appeal to possibility) – a statement that takes something for granted because it would probably be the case (or might be the case).

  • Something can go wrong (premise).
  • Therefore, something will go wrong (invalid conclusion).
    • If I do not bring my umbrella (premise)
    • It will rain. (invalid conclusion).
  • Dave: Did you know that Jesus liked to dress up as a woman and sing show tunes?
  • Tim: And why do you say that?
  • Dave: You have to admit, it is possible!
    • We cannot assume Jesus liked to dress like a woman while belting out 2000-year-old show tunes based on the possibility alone. This also includes the argument from ignorance fallacy — concluding a possibility based on missing information (an outright statement that Jesus did not do these things).

Exception:  There are no exceptions. Possibility alone never justifies probability.