A fallacy is an invalid form of argument or an instance of incorrect reasoning. Fallacies are either formal fallacies or informal fallacies.
A formal fallacy is an error in logic that can be seen in an argument’s form.¹ All formal fallacies are specific types of non sequiturs.
One example of a formal fallacy includes an appeal to probability where one takes something for granted because it would probably be the case.¹ Another example of a formal fallacy might include the conjunction fallacy where the assumption that an outcome simultaneously satisfying multiple conditions is more probable than an outcome satisfying a single one of them.¹
Example of a causation fallacy³:
“I saw a magpie and ten minutes later, I crashed my car, therefore, magpies are bad luck.”
Informal fallacies are arguments that are fallacious for reasons other than structural flaws and which usually require examination of the argument’s content.²
An example of an informal fallacy may include an argument from ignorance, which is assuming that a claim is true because it has not been proven false or cannot be proven false. Another example of an informal fallacy might include circular reasoning when the reasoned begins with what he or she is trying to end up with.¹
1. Blackwell Reference Online. Formal Fallacy. Retrieved May 22, 2014, from http://www.blackwellreference.com/public/tocnode?id=g9781405106795_chunk_g97814051067957_ss1-95
2. Blackwell Reference Online. Informal Fallacy. Retrieved May 22, 2014, from http://www.blackwellreference.com/public/tocnode?id=g9781405106795_chunk_g978140510679510_ss1-120
3. Your Dictionary. Examples of Fallacies. Retrieved May 22, 2014, from http://examples.yourdictionary.com/examples/examples-of-fallacies.html© BrainMass Inc. brainmass.com March 26, 2019, 4:32 pm ad1c9bdddf