I’m searching for an idiom that would mean the following: The situation is obvious to an untrained eye.

For example, say someone looked unwell, perhaps with a cold and one person says to another about a third party,

"You don’t require a doctor to understand that he has a cold, because it’s ____________ [obvious to an untrained eye as to what is going on]".

Thank you!


7 Answers 7


It's not rocket science
It's not brain surgery

These are often used when someone is trying to make something more difficult than it really is.

From the OED:

brain surgery n. surgery performed on the brain, neurosurgery; (hence humorously) something requiring a high level of intelligence or expertise (frequently in negative constructions, implying that something is not difficult); cf. rocket science n. at rocket n.5

rocket science n. (a) the science of rockets and rocket propulsion; (b) colloq. something requiring a high level of intelligence or expertise; frequently in negative constructions, implying that something is relatively simple.

  • 14
    Or sometimes... it's not rocket surgery.
    – Tushar Raj
    Oct 10, 2018 at 12:38
  • 1
    I know it is used as an idiom like this, but "rocket science" annoys me. "Rocket science is not hard, you can explain most of it to a bright 8-year-old. Rocket engineering on the other hand..." Oct 10, 2018 at 16:44
  • 1
    Back in a school's rocket club I was in, a common phrase was, "it's only rocket surgery!"
    – Phoenix
    Oct 10, 2018 at 16:59
  • 1
    @RobertColumbia Relevant: youtube.com/watch?v=THNPmhBl-8I
    – Kevin
    Oct 10, 2018 at 17:49
  • 1
    @Kevin: That was gold!
    – Tushar Raj
    Nov 28, 2018 at 13:36

One such idiom is: no-brainer.

"You don’t require a doctor to understand that he has a cold, because it’s a no-brainer".


n. an easy question that takes no thinking to answer; a simple problem that requires no intellect to solve; a dilemma that requires no pondering to resolve.

McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.


I propose common sense. It has a generally positive connotation.

common sense

n. Sound judgment not based on specialized knowledge.

American Heritage® Dictionary of the English Language, Fifth Edition. (2011). Retrieved from https://www.thefreedictionary.com/common+sense

  • I think the most common form for the specific example used by the OP would be "it's just common sense." Oct 10, 2018 at 14:28

Any Fool

In England this is an idiomatic expression for "a person with the minimum level of skill and knowledge that everyone should have".

Any fool can see..

  • You don’t require a doctor to understand that he has a cold, any fool can see that
  • Any fool can see he has a cold, you don't need to be a brain surgeon.

Any fool knows...

  • Any fool knows you have to turn it on first

Any fool can...

  • Any fool can hit his thumb with a hammer, but it takes someone special to hit his head.
  1. It's easy as ABC.

Source : idioms.thefreedictionary.com (note the word intuitive.)


It's plain as day. The expression plain as day means that it is obvious, simple to recognize or understand, straightforward. That is to say, if you can recognize daytime or see the sun in the sky, then you will recognize something that is plain as day.

It's as plain as day that he has a cold.


"A monkey could (do/see) it." This is probably a little more common with "do" instead of "see", but it works either way.

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