Logical Fallacies and Causal Relationships

Learning Objectives:

  • Identify logical fallacies relating to causal relationships.

A logical fallacyA mistake in reasoning; faulty thinking that weakens an argument or leads to an incorrect conclusion. is faulty reasoning used to support an ideaA thought, opinion, or impression., theoryIn science, a well tested and widely accepted explanation for a phenomenon. Theories incorporate facts, observations, experiments, laws, and careful reasoning. In more general usage, theory may merely mean an unproven idea, speculation, or guesswork., thesisAn overall argument, idea, or belief that a writer uses as the basis for a work., or hypothesisA preliminary explanation that needs further study before it can be accepted. A hypothesis is stronger than a guess but less supported than a theory.. When a careful reader identifies a logical fallacy, it may cause him or her to question the validity of the entire argumentA set of statements or reasons making a case for or against something., so it is important to identify logical fallacies in both your own and others' writing.

Think of logical fallacies as cracks in the foundation of a home. Some may be nearly naked to the invisible eye; others are large, gaping crevices. Either has the potential to eventually or suddenly cause your foundation to crumble and your house to fall. Logical fallacies in a textWords that make up a book, essay, article, poem, or speech. can work in the same fashion. Some may be challenging to spot; others may be quite obvious. Learning to identify and understand logical fallacies will help you better analyzeTo make a thoughtful and detailed study of something. the writing of others and know which arguments are strongest upon which to base your own reasoning.

In this lesson, you will be introduced to seven common logical fallacies.

  1. Slippery slope

The slippery slope fallacy is basically how it sounds. It is a premise that if "A" happens, then so will "B...C...D..." and so forth, through a series of small steps.

For example, if I do not get straight A's in high school, then I won't get into an Ivy League college, then I will not get a good job, and I will be stuck in a terrible job for the rest of my life.

  1. Post hoc fallacy or false cause

This fallacy implies that "A" caused "B" because "A" happened before "B."

For example, I chose not to wash my sports uniform. Our team won the game. We won the game because I did not wash my uniform. I will no longer wash my uniform before games so that we will continue to win.

  1. Genetic fallacy

This is the assumption that since "A" is associated with "B," "A" and "B" share the same good and bad traits.

For example, Hitler loved the work of the music composer Wagner. Since Hitler is associated with Wagner and Hitler was a terrible human being, Wagner must also be an equally terrible person.

  1. Cherry picking

Cherry picking is a fallacy that relies upon choosing only that dataFacts, numbers, or information. or evidenceFacts, statistics, or expert testimony that supports a claim. that will lead to your desired outcome rather than revealing the full picture.

This is not uncommon in the courtroom. Some attorneys may choose to ignore the evidence that goes against their cases, setting forth only the "facts" that support a verdict in favor of their clients.

  1. Fallacy of the single cause

This is the assumption that an event has only one cause.

For example, in the instance of a shutdown of a large corporation, we begin to ascribe one reason why it happened. We might say that the business mismanaged its finances and went bankrupt. However, there is usually more than a single cause for major events; in this case, it might also be that the company has engaged in illegal activities or the corporation was taken over by a global conglomerate in addition to the bankruptcy.

  1. Correlation proves causation

This is the logical fallacy that because "A" and "B" happen to occur at the same time, there is a causalDescribing or suggesting a cause. relationship.

For example, whenever I develop a rash, I put lotion on it and the rash goes away. The lotion must cause the rash to disappear. However, the rash may just go away eventually whether I put lotion on it or not.

  1. Reversing causal direction

This is the implication that "A" causes "B" without considering that "B" causes "A."

For example, each night when the streetlights turn on, the sun begins to set. The streetlights (A) must cause the sun to set (B). However, the streetlights obviously have no influence on the sun. The sun setting (B) is the reason the streetlights come on (A).