Accused of a fallacy? Suspect a fallacy? Ask Dr. Bo and the community!

Quickly register to comment, ask and respond to questions, and get FREE access to our passive online course on cognitive biases!

one moment please...

Appeal to Definition

(also known as: appeal to the dictionary, victory by definition)

Description: Using a dictionary’s limited definition of a term as evidence that term cannot have another meaning, expanded meaning, or even conflicting meaning.  This is a fallacy because dictionaries don’t reason; they simply are a reflection of an abbreviated version of the current accepted usage of a term, as determined by argumentation and eventual acceptance.  In short, dictionaries tell you what a word meant, according to the authors, at the time of its writing, not what it meant before that time, after, or what it should mean.

Dictionary meanings are usually concise, and lack the depth found in an encyclopedia; therefore, terms found in dictionaries are often incomplete when it comes to helping people to gain a full understanding of the term.

Logical Form:

The dictionary definition of X does not mention Y.

Therefore, Y must not be part of X.

Example #1:

Ken: Do you think gay marriage should be legalized?

Paul: Absolutely not!  Marriage is defined as the union between a man and a woman—not between two men or two women!

Ken: Did you know that in 1828 the dictionary definition of marriage included, “for securing the maintenance and education of children”?  Does that mean that all married couples who can’t or choose not to have children aren’t really married?

Paul: No, it just means they need to buy updated dictionaries.

Ken: As do you.  The current Merriam-Webster Dictionary includes as a secondary definition, “the state of being united to a person of the same sex in a relationship like that of a traditional marriage.”

Explanation: The dictionary does not settle controversial issues such as gay marriage—it simply reports the most current accepted definition of the term itself while usually attempting to remain neutral on such controversial issues.

Example #2:

Armondo: Mrs. Patterson was wrong to knock off 10 points off my oral presentation because I kept using the word, “erection” instead of building.

Felix: That was hilarious, but did you honestly think you would not get in trouble?

Armondo:  No, my dictionary says that an erection is a building.

Explanation: Armondo may be right, but the dictionary is not the final authority on all issues, especially social behavior.  More modern usage, especially in a high school setting, takes precedence in this case.

Exception: The dictionary works well when the term in question is a result of a misunderstanding or ignorance.  For example:

Ken: Do you accept biological evolution?

Paul: No.  Because I know for a fact that my grandmother was not a monkey.

Ken: Good Lord.

Tip: Don’t be afraid to argue with authority if you believe you are right -- even when that authority is the dictionary.


This is an original logical fallacy named by the author, but the victory by definition form has the following source:

Govier, T. (2009). A Practical Study of Argument. Cengage Learning.

Registered User Comments

Thursday, December 15, 2016 - 06:45:43 PM
So, if somebody's claim involves a definition for something, then what is the best thing to reference when arguing with them, so as to ensure the soundness of your own argument? If making a scientific argument, would it be best to reference scientific textbooks, for example?

login to reply
1 reply
0 votes
Reply To Comment

Bo Bennett, PhD
Thursday, December 15, 2016 - 06:56:43 PM
Textbooks , encyclopedias, or scientific papers are good for science terms. Otherwise, look at a number of dictionary entries to see if the definition being used is common or a one-off. And you can always conceded that "if we are going by that definition...", then demonstrate that your definition is more common (if it is).

login to reply
1 votes
Reply To Comment

Become a Logical Fallacy Master. Choose Your Poison.

Logically Fallacious is one of the most comprehensive collections of logical fallacies with all original examples and easy to understand descriptions; perfect for educators, debaters, or anyone who wants to improve his or her reasoning skills.

Get the book, Logically Fallacious by Bo Bennett, PhD by selecting one of the following options:

Not Much of a Reader? No Problem!

Enroll in the Mastering Logical Fallacies Online Course. Over 10 hours of video and interactive learning. Go beyond the book!

Enroll in the Fallacy-A-Day Passive Course. Sit back and learn fallacies the easy way—in just a few minutes per day, via e-mail delivery.

Have a podcast or know someone who does? Putting on a conference? Dr. Bennett is available for interviews and public speaking events. Contact him directly here.

About Archieboy Holdings, LLC. Privacy Policy Other Books Written by Bo
 Website Software Copyright 2019, Archieboy Holdings, LLC.