Tautology | Meaning, Definition & Examples
In rhetoric, a tautology is the unnecessary repetition of an idea using different words (e.g., “a free gift”).
Tautologies are often considered to be a stylistic fault that should be avoided. However, they can also be used effectively as a rhetorical device or figure of speech.
The term may also refer to a logical tautology: a statement that is true in all circumstances because it includes all possibilities (e.g., “it will snow tomorrow or it will not”).
Types of tautology
There are two main types of tautology. One is relevant in the context of rhetoric, the other in the context of formal logic.
A rhetorical tautology is the redundant restatement of an idea of concept.
Rhetorical tautologies occur when additional words are used to convey a meaning that is already expressed or implied. For example, the phrase “a new innovation” is a tautology because “innovations” are by definition “new”.
Rhetorical tautologies are usually perceived as bad style because they are needlessly repetitive. However, they can also be used to effectively emphasise a particular aspect of an idea (for this reason, they’re often used in political speeches and advertising slogans).
A logical tautology is a proposition or statement that is always true because it excludes no logical possibility.
Logical tautologies don’t express any meaningful claim about the world. They usually take the form of “either/or” statements (e.g., “It will happen or it won’t”).
Some logical tautologies involve circular reasoning, meaning they support their initial claim by referring back to the claim again. In these instances, the premise is simply repeated (e.g., “blue is blue”).
While logical tautologies are typically logically redundant, they’re sometimes used in a non-literal sense (often to express inevitability).
Should you avoid using tautologies?
Using tautologies is normally considered a fault of style and should be avoided in formal contexts like academic writing.
Tautologies often occur when a synonym (or a word that conveys a similar idea) is included in a sentence. In these instances, you can remove the superfluous word to make your writing more concise.
However, tautologies are often also used effectively in literature, political speeches, advertising, and everyday speech to emphasise something or convey a sense of certainty.
For example, while the expression “I saw it with my own eyes” is tautologous (you cannot see something with someone else’s eyes), it’s commonly used to emphasise that something is true even though it seems unbelievable.
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Frequently asked questions
- What is a rhetorical tautology?
A rhetorical tautology is the repetition of an idea of concept using different words.
Rhetorical tautologies occur when additional words are used to convey a meaning that has already been expressed or implied. For example, the phrase “armed gunman” is a tautology because a “gunman” is by definition “armed.”
- What is a logical tautology?
A logical tautology is a statement that is always true because it includes all logical possibilities.
Logical tautologies often take the form of “either/or” statements (e.g., “It will rain, or it will not rain”) or employ circular reasoning (e.g., “she is untrustworthy because she can’t be trusted”).
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