they must have

USAGE SUMMARY

"they must have" is a correct and usable form of written English.
This is a common phrase used when making a deduction based upon certain evidence. For example, "The roses in front of the house have wilted; they must have been there for days."

✓ Grammatically correct

News & Media

Science

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

They must have new leadership.

TechCrunch

They must have some stamina.

Independent

They must have liked 2012.

The New York Times - Arts

They must have been listening.

Independent

And they must have talent.

The New York Times - Sports

"They must have done something".

The New York Times

"They must have been exhausted.

Independent

They must have gotten Qaddafi".

The New York Times

They must have practiced.

The New York Times - Sports

They must have them.

The New York Times

"They must have spent thousands on it.

The New Yorker

Expert writing Tips

Best practice

Use "they must have" to express a logical deduction based on available evidence. Ensure the context provides sufficient clues to support the inference.

Common error

Avoid using "they must have" when there's no clear basis for the deduction. A strong inference requires some supporting information, otherwise it appears as a wild guess.

Linguistic Context

The phrase "they must have" functions as an epistemic modal, expressing a high degree of certainty or logical deduction about a past event or state. It suggests that based on available information, it is highly probable that something occurred or was true. As Ludwig AI confirms, this phrase is grammatically correct and commonly used to express deductions.

Expression frequency: Very common

Frequent in

News & Media

67%

Science

17%

Wiki

5%

Less common in

Formal & Business

3%

Encyclopedias

0%

Reference

0%

Ludwig's WRAP-UP

The phrase "they must have" is a versatile tool for expressing logical deductions about past events or states. As Ludwig AI confirms, it's grammatically sound and frequently used. Its prevalence in news sources and across varied authoritative publications underscores its broad applicability. When using "they must have", ensure that the context provides sufficient evidence to support the inference, avoiding overuse in the absence of clear clues. Consider alternatives like "it is likely they had" or "presumably, they were in possession of" for nuanced expression or formal contexts. "They must have" is your go-to phrase when the pieces of the puzzle align to reveal a probable truth.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

it is likely they had

Replaces the modal verb construction with an adverbial phrase indicating probability.

they probably did

Uses an adverb to indicate probability, simplifying the modal verb construction.

it's reasonable to assume they did

Emphasizes the reasonableness of the assumption, adding a layer of justification.

one can assume they possess

Formalizes the deduction, replacing "must have" with "can assume they possess".

it's almost certain they owned

Conveys a high degree of certainty regarding their possession.

presumably, they were in possession of

Adds a nuance of presumption to their possession, suggesting it's based on available evidence.

it stands to reason that they enjoyed

Indicates a logical conclusion about their enjoyment based on the circumstances.

undoubtedly, they were equipped with

Expresses complete certainty that they had the necessary equipment.

it's safe to say that they carried

Suggests that it's a reliable assumption that they carried something.

logically, they are required to present

Indicates that it's a requirement to present something based on logical reasoning.

FAQs

How can I use "they must have" in a sentence?

Use "they must have" to express a logical deduction or inference based on evidence. For example, "The lights are on; "they must have" arrived."

What's a more formal way to say "they must have"?

In formal contexts, consider using alternatives like "it is likely they had" or "it is reasonable to assume they did" to express a similar level of deduction.

Is "they must of" correct instead of "they must have"?

No, "they must of" is grammatically incorrect. The correct form is "they must have", where "have" is part of the modal perfect construction.

When should I not use "they must have"?

Avoid using "they must have" when you have direct knowledge or evidence. It's best suited for situations where you're making an inference rather than stating a known fact.