Appeal to Definition
The fallacy of using a dictionary's limited or current definition of a term as definitive evidence that the term cannot have other, expanded, or conflicting meanings, ignoring that dictionaries report usage and are not final authorities on meaning.
THE IDEA
Definition
An appeal to definition treats a dictionary entry as proof that a word cannot have any other meaning. Dictionaries summarize usage; an entry may omit a specialized, emerging, or context-dependent sense. A definition can help clarify a discussion, but it does not by itself settle a substantive dispute.
Logical Form
Person 1 makes a claim about a term. Person 2 cites a dictionary definition as authoritative proof that Person 1’s usage or understanding is wrong.
Examples
Example #1
Person 1: "Gay marriage is unnatural." Person 2: "According to the Merriam-Webster dictionary, marriage is 'the state of being united to a person of the opposite sex as husband or wife.' So, you are wrong." Explanation: The quoted dictionary wording cannot settle whether same-sex marriage is natural or should be recognized. The reply also fails to address the first speaker’s claim.
Example #2
Person 1: "Armondo, stop being a dick." Armondo: "According to the dictionary, a dick is 'a detective' or a 'penis.' Clearly, I am neither, so your argument is invalid." Explanation: The complaint uses a slang meaning. Listing other meanings does not address what the speaker intended; the conversational context matters.
Exception
A dictionary can resolve a misunderstanding when the relevant issue is the conventional meaning of a term.
Tip
When a definition seems inadequate, explain the usage or context it leaves out.
When to use it
Debating the definition of 'marriage' in discussions about same-sex unions.
Arguing about the meaning of technical terms in a field where usage has shifted (e.g., 'theory' in science vs. everyday use).
Interpreting legal or contractual language where dictionary definitions may conflict with intent or context.
Critiquing someone who dismisses a slang or emerging meaning by citing a static dictionary entry.
FROM THEORY TO EVERYDAY LIFE
In practice
Example 1: Gay Marriage Definition
Person 1: "Gay marriage is unnatural." Person 2: "According to the Merriam-Webster dictionary, marriage is 'the state of being united to a person of the opposite sex as husband or wife.' So, you are wrong." Explanation: The quoted dictionary wording cannot settle whether same-sex marriage is natural or should be recognized. The reply also fails to address the first speaker’s claim.
Example 2: Slang Usage
Person 1: "Armondo, stop being a dick." Armondo: "According to the dictionary, a dick is 'a detective' or a 'penis.' Clearly, I am neither, so your argument is invalid." Explanation: The complaint uses a slang meaning. Listing other meanings does not address what the speaker intended; the conversational context matters.
A MOMENT TO REFLECT
Put it to work.
When might a dictionary definition be insufficient or misleading as evidence in an argument?
Can you think of a time when someone used a dictionary to shut down a valid point? How could you counter that?
How do changes in usage limit what a single dictionary entry can establish?
CONTINUE THE CONVERSATION
Source texts
- Logically Fallacious - The Ultimate Collection of Over 300 Logical Fallacies