What Does "be based on" Mean?
- Meaning: The expression "be based on" indicates that something uses a particular fact, idea, or situation as its foundation, starting point, or underlying justification.
- Compositionality: The meaning is semi-idiomatic. While "base" relates to a foundation, the specific combination with "on" creates a stable phrasal unit used to link a result to its source or evidence.
- Register: This expression is neutral to formal. it is ubiquitous in academic writing, journalism, legal documents, and professional discourse, though it is also perfectly acceptable in standard conversation.
How to Use It
- Grammatical pattern: It follows the passive construction [Subject] + [be-verb] + based + on + [Noun Phrase]. The subject is the thing being created or evaluated, and the object of the preposition "on" is the foundation.
- Complements: It is almost always followed by a noun phrase representing evidence, facts, data, or a source text (e.g., "based on a true story").
- Separability: As a passive construction, the components "based on" generally stay together. However, you can insert an adverb for emphasis: "is largely based on" or "is firmly based on."
- What sounds unnatural: Using the wrong preposition is the most frequent error. Saying "based at" or "based of" is grammatically incorrect when discussing a logical foundation.
Real-World Examples
These examples are sourced from be based on on Ludwig.guru.
"Policymaking should be based on evidence." — theguardian.com
"Salary will be based on experience." — cornell.edu
"Conservation has to be based on science." — nytimes.com
"One will be based on Ferguson's biography." — newyorker.com
"Which answers seem to be based on opinion and which seem to be based on facts?" — nytimes.com
Similar Phrases and Alternatives
| Phrase |
Context |
| derive from |
Suggests a clear origin or source; more formal and often used in linguistics or science. |
| rely on |
Emphasizes dependency on a specific factor or piece of data. |
| grounded in |
Similar to "based on" but implies a deeper, more fundamental connection to a theory or principle. |
| rest on |
Often used for arguments or theories that depend entirely on a specific premise. |
| stem from |
Focuses on the root cause or origin of a situation. |
| draw on |
Indicates using a resource or experience as a source of information or inspiration. |
Common Mistakes
- Wrong Preposition: Learners often use the incorrect preposition, such as saying 'based in' when referring to a logical foundation or 'based from' when referring to a source. Note that "based in" is only correct for physical locations (e.g., "The company is based in London").
- Active vs. Passive: Using "base on" in the active voice requires an object (e.g., "I base my opinion on facts"), whereas learners sometimes incorrectly omit the "be" verb in passive contexts (e.g., "The movie based on a book" should be "The movie is based on a book").
Quick-Reference Summary
| Expression |
Meaning |
Grammatical Pattern |
Register |
| be based on |
To use something as a foundation or evidence |
Subject + be + based + on + Object |
Neutral / Formal |
FAQs
Can the words in the phrase be separated by other words?
While the passive participle and the preposition usually stay together, you can place an adverb between them to modify the degree of the connection. For example, you might say "the decision was based largely on the report." However, the subject and the prepositional phrase cannot be swapped without changing the entire sentence structure.
What is the difference between being based on and being grounded in?
While both expressions refer to a foundation, be based on is more general and frequently used for data, facts, or source material. In contrast, be grounded in often carries a more metaphorical or philosophical weight, suggesting that an idea is firmly established within a specific theoretical framework or set of values.
Should I use based on or based in when talking about information?
You should always use based on when referring to a logical foundation, evidence, or a source of information. Learners often use the incorrect preposition, such as saying based in when referring to a logical foundation or based from when referring to a source, but based in should be reserved strictly for physical locations, such as a company's headquarters.