Logical Fallacies and Analysis

Learning Objective:

  • Identify logical fallacies relating to analysis.

A logical fallacyA mistake in reasoning; faulty thinking that weakens an argument or leads to an incorrect conclusion. is faulty reasoning upon which 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. is based. This is especially important when analyzingTo make a thoughtful and detailed study of something. other people's writing. Should you rely upon an author's thoughts and argumentsA set of statements or reasons making a case for or against something. as evidenceFacts, statistics, or expert testimony that supports a claim. in an essayA short piece of writing that focuses on at least one main idea. Some essays are also focused on the author's unique point of view, making them personal or autobiographical, while others are focused on a particular literary, scientific, or political subject. , an unidentified logical fallacy can weaken your writing and undermine your entire thesis statementA brief statement that identifies a writer's thoughts, opinions, or conclusions about a topic. Thesis statements bring unity to a piece of writing, giving it a focus and a purpose. You can use three questions to help form a thesis statement: What is my topic? What am I trying to say about that topic? Why is this important to me or my reader?.

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

  1. Circular reasoning: Supporting an argument by restating the argument.

I did not deserve a D on the paper because I have always been an A+ student.

  1. Bandwagon appeal: Implies that because the majority of people believe that X is true then it must be valid because so many people believe it.

You should use Clean and Fresh shampoo because it is the number one selling shampoo in the United States.

  1. Ad hominem: An attack on a person's character and personal traits to weaken his or her argument.

That man is not competent to run for city council; he was arrested when he was a teenager for underage drinking and public intoxication.

  1. Red herring: Claims that are misleading to distract from the argument at hand.

Can you believe that the cop pulled me over for going five miles over the speed limit? Police need to spend all their time getting the really dangerous offenders off the street, like murderers.

  1. Non sequitur: A conclusion that is disconnected from the premise that precedes it.

The moon landing must have been faked. There are "photos" of fairies and the Loch Ness monster.

  1. False analogy: A claim that since A is like B, A has the same properties that B has.

I loved the Harry Potter series by JK Rowling so much that I am sure that I will love her newest book.

  1. Hasty generalization: Coming to a conclusion with the briefest look at the evidence.

I just saw the inside of my accountant's car, and it was an absolute mess. I am not sure we should hire her to be our CPA; she would be as careless with our finances.

  1. Moral equivalence: A claim that compares A with B to prove that A is as bad or good as B.

You might want to think twice before going out with Justin; his brother has a new girlfriend every two weeks.