Identifying errors in reasoning that occur in everyday language.
A fallacy is a defect in an argument that consists of something other than a false premise alone. Unlike formal fallacies, which are identified by inspecting the "shape" of the argument, informal fallacies can only be detected by examining the content and context of the argument.
In these fallacies, the premises are logically irrelevant to the conclusion, although they may seem psychologically relevant.
Attacking the character or circumstances of the person making the argument instead of addressing the argument itself.
Example: "You shouldn't believe his theory on climate change; he was once arrested for shoplifting."
Claiming something is true just because many people believe it or it is popular.
Example: "Everyone is using this brand of phone, so it must be the best one available."
Using a threat of harm to make someone accept a conclusion.
Example: "You should agree with my decision, unless you want to find yourself looking for a new job."
Using pity or sympathy to win support for an argument.
Example: "Professor, I deserve an 'A' because my car broke down and my dog is sick."
Arguing that something is true because it hasn't been proven false (or vice versa).
Example: "No one has proven that ghosts don't exist; therefore, they must exist."
These occur because the premises presume what they are supposed to prove.
Circular reasoning where the conclusion is hidden in the premises.
Example: "God exists because the Bible says so, and the Bible is true because it's the word of God."
Asking a question that has a presupposition built into it.
Example: "Have you stopped cheating on exams?" (Both Yes and No imply you used to cheat).
These occur due to shifts in the meaning of words or phrases within an argument.
Using the same word with two different meanings in the same argument.
Example: "The sign says 'Fine for Parking Here,' so since it's fine, I'll park my car."
Occurs when a statement is awkward or poorly constructed, leading to double meanings.
Example: "The professor said he would give a lecture on heart failure in the biology lab." (Is the lecture in the lab, or is the heart failure occurring in the lab?)