Tautology – Definition, Types & Use In Academic Writing

27.09.23 Academic writing Time to read: 7min

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“It is what it is” – a phrase often used to express a resigned acceptance of circumstances – also serves as a simple example of a tautology. In logic and rhetoric, it refers to a statement that is inherently true in all possible circumstances, without providing any new information and often considered as a stylistic error. While it may appear as mere repetition and redundancy, it serves critical roles in various fields, especially in academic writing. This article will provide an overview of this topic.

Tautology in a nutshell

A tautology describes a statement that is true by virtue of its logical form alone. It represents a needless repetition of an idea, statement, or word.

Definition: Tautology

A tautology is a statement that expresses the same idea or proposition in a redundant or repetitive manner. The word has its origins in ancient Greek, deriving from the Latin “tautologia”, which is a combination of two Greek words: “tauto” (the same or identical) and “logia” (saying or expression). Combining both means “saying the same thing” or “repeating the same word or idea unnecessarily”. Essentially, it is a proposition that inherently confirms itself and cannot be proven false. Although they are sometimes considered redundant or lacking informative value, they play a crucial role in persuasive writing and descriptive writing, as well as, in several fields, including mathematics, philosophy, and computer science, where they establish fundamental principles.

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Historical background

“Tautology” is a concept that has a long history in philosophy, logic, and linguistics. It draws attention to the fact, that it is basically a statement or proposition, that is true by necessity or by virtue of its logical form and often results in redundancy or the repetition of meaning. An overview of the historical background is here.

  1. Ancient Philosophy
    The idea of saying the same thing twice can be traced back to ancient Greek philosophy. Parmenides, for instance, argued that only what is, is, and what is not, is not, thus emphasizing the importance of tautological reasoning in discussing fundamental truths.
  2. Stoicism
    The Stoic philosophers, particularly Chrysippus, made significant contributions to the development of propositional logic. They introduced the concept of a “necessary consequence,” which is similar to the stylistic device in modern logic.
  3. Medieval Philosophy
    Medieval philosophers, including Thomas Aquinas, engaged in discussions of logic and language, which laid the foundation for later developments in the study of this stylistic device.
  4. Modern Logic
    The formal study gained prominence in the modern era, particularly with the work of logicians like Gottfried Wilhelm Leibniz and George Boole.
  5. 20th Century and Beyond
    Furthermore, it became a central concept in mathematical logic, propositional logic, and predicate logic during the 20th century. In linguistics, it is studied as a phenomenon where the same idea is repeated in different words or phrases, often for emphasis or rhetorical effect. This is distinct from logical statements, but shares the idea of redundancy.

Examples of tautologies

Here’s an overview of common examples, used in everyday speech:


  1. You’ll either pass or fail the exam.
  2. Fire is hot.
  3. Water is wet.
  4. The sun is bright during the day.
  5. A bachelor is an unmarried man.
  6. You’re either alive or not alive.
  7. It is either yes or no.

Types of tautologies

In grammatical terms, there are two primary types: one is related to rhetoric, while the other type applies to formal logic.

Rhetorical tautology

This type is also known as a redundant restatement, involving the unnecessary repetition of an idea or a concept.

This type occurs when extra words are used to imply that something has been said or expressed already. Phrases like “new innovation” or “free gift” exemplify a tautology because “innovations” imply newness and a “gift” is always free. They are considered as “poor stylistic choices” due to their needless redundancy. However, they serve as effective tools to emphasize an aspect or idea, especially in advertising slogans and political speeches.


  • The officer said there was an armed gunman.
  • I came to collect my free gift.
  • I am just a human being!

Logical tautology

A logical tautology can be used in various situations because the proposition or statement is always true. Certain logical statements use circular reasoning. They repeat the original idea, like saying “all squares have four sides.” They don’t tell us anything new about the “real world,” and they often follow a simple “either/or” pattern, like “It will happen, or it won’t.”


  • It will or it will not.
  • She is famous because people like her.
  • It will rain or it will not

Non-literal logical tautology

Although logical statements are generally characterized by logical redundancy, they are occasionally employed in a figurative manner, often to convey a sense of inevitability.


  • Boys will be boys. 
  • It is what it is.

However, using them in academic essays is not very common. Therefore, you should focus on expressing your ideas in a clear and logical way, avoiding unnecessary repetition. Always follow the conventions and guidelines of your specific academic field and the style guide you are using when writing for academic purposes.

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Tautology vs. pleonasm

Both are forms of redundancy in language, but they differ in their nature and usage:

Tautology: The redundancy occurs at the level of meaning or logic. It involves the use of repetitive words and phrases with the same meaning, typically in an obvious or unnecessary way. It draws attention to the repetition of ideas.


  • “I saw it with my own eyes!” (In this case, “with my own eyes” is redundant because you’re unable to see through other eyes.)

Pleonasm: This is a specific type of redundancy where the repetition occurs at the word or phrase level. It involves using more superfluous words than necessary to convey a particular meaning.


  • “He added an extra bonus to the gift.” (In this case, the word “extra” is unnecessary because a bonus is already something additional or extra.)

When to use “tautology”

Tautologies are typically avoided in formal writing because they introduce redundancy and do not add substantive information. However, there are some specific situations where you might use them intentionally or where they may be acceptable:


  1. Emphasis: They can be used for emphasis to underscore a point or idea. In persuasive or rhetorical writing, tautologies can be used to draw attention to an aspect or idea. However, be careful not to overuse them. Otherwise, your academic writing might be viewed as redundant and uninformative.
  2. Rhetorical effect: In creative writing, poetry, or certain types of rhetoric, they can be employed for a stylistic effect. They can create a sense of rhythm, repetition, or reinforcement. It can be a rhetorical device, a figure of speech, or a stylistic error.
  3. Slogans and Advertising: Sometimes, they are used in advertising slogans or catchphrases for simplicity and memorability. Phrases like “free gift” or “new innovation” are tautological, but can be effective in marketing and advertising.
  4. Humor: They can be used humorously in needless repetition to point out the obvious or to mock redundancy intentionally.

Note: Even in these situations, it’s important to use them sparingly and with a clear purpose. Overusing them can make your writing sound repetitive and imprecise.

Synonyms for “tautology”

The following illustrates synonyms for the word “tautology”.

Synonym Examples
Redundancy Unnecessary repetition is redundancy.
Unnecessary repetition is tautology.
Repetition Communication is less effective due to the constant repetition.
Communication is less effective due to the constant tautologies.
Superfluity His explanation contained a superfluity of unnecessary information.
His explanation contained a tautology of unnecessary information.


It is a proposition or statement in logic that is true by definition, meaning it is always true and cannot be false under any circumstances. In other words, it is a statement that is inherently self-evident and does not provide any new information.

An example could be “it is what it is” or “all humans are mammals”.

This depends on how you want to use them. However, they can be considered redundant and uninformative, so you shouldn’t use them in your academic writing.

This stylistic device uses different words to say the same thing twice. They can be used to emphasize a point or clarify a statement by restating it in a redundant manner.

Both terms are forms of redundancy in language, with different applications and meanings:

Tautologies are used for emphasis, clarification, or to highlight a point.

Pleonasm is often considered a stylistic error or grammatical error in writing and speech.