So my client is asking to quickly tell him if a certain task is doable. But there is no way of just quickly checking its feasibility except for actually performing the entire task. How do I intimate this thing in a nice but solid manner? Is there a phrase or something that would convey my position?

  • 8
    Say just that. Always be plain with your clients, they will thank you! Jun 30, 2017 at 11:31
  • 3
    How about "I don't know".
    – Phil Sweet
    Jun 30, 2017 at 19:16
  • It's the fundamental answer by turing to the decidability problem, of course. The halting theorem.
    – Francesco
    Jun 30, 2017 at 20:19
  • This is a great question...
    – barbecue
    Jul 1, 2017 at 22:31

6 Answers 6


The idiomatic expression, at least in the US, is "We won't know until we try."

  • 5
    To my (American) ear, this makes it sound like a very ambitious/kind of crazy project--Can we get to the moon in this decade? We won't know until we try! I don't know whether that's a good thing or a bad thing in this case Jun 30, 2017 at 15:30

In the software world, we'd say that we'd have to create a proof of concept.

  • 1
    I really think this should be the accepted answer. To say you need to "do a proof of concept" conveys exactly what the original question is asking.
    – Mark Meuer
    Jun 30, 2017 at 17:39
  • 14
    "Proof of concept" tends to mean a "scaffolded" version of a product. Many of the functions of the final product would be omitted.
    – Hot Licks
    Jun 30, 2017 at 22:06
  • @HotLicks While you need to do the whole task you very well might not need to do the whole task to the whole set of inputs. Do A, B, C when the true project will need 3x A, 2x B, 4x C. Jul 2, 2017 at 4:04

"There's (only) one way to find out" with or without the word "only" kind of indicates "the best way to see what will happen is to try it"

  • 1
    I think this is the best answer, but I don't know why you put "only" in parentheses. I've never heard anyone say "There's one way to find out", so the word "only" presumably always goes there, no?
    – Hack-R
    Jul 2, 2017 at 14:32
  • It's commonly used either way, with or without the "only". The reason to insert "only" in this case is to emphasize the point the OP wishes to make.
    – Lee Mosher
    Jul 2, 2017 at 14:40

An informal alternative to Hot Lick's contribution is

suck it and see UK informal - Cambridge Dictionary

to try something to find out if it will be successful: I'm not sure whether this paint is the right colour for the bedroom - we'll just have to suck it and see.

The phrase is in common use in Australian English. It might come across as off-colour on first presentation, but I think the imagery is derived from the taste-testing of confectioneries (e.g. lollipops): the only way to know how exactly it tastes is to sample it. I've highlighted the phrase in the usage instances quoted below.

Here's an instance of the phrase as a title in The Economist, a mainstream publication for the financial industry. The use of the phrase as a pun (in an article about a vacuum-cleaner entrepreneur) supports the assertion that the phrase is widely used.

Here are a few more instances of the phrase in use in a positive light:

And finally, here's the phrase used in a client brochure. It portrays the approach in a negative light and is further evidence of the phrase's acceptance in a commercial setting:

  • The secret to getting the most out of a CDN campaign is to create content that is share-worthy. You can’t afford to take a suck-it-and-see approach. - Quantum Linx
  • 13
    Thanks. "Suck it" sounds a bit too informal for a client though. :D
    – dotNET
    Jun 30, 2017 at 12:03
  • 1
    I would say this is more than informal. I'd be offended and question the professionalism of someone who used that phrase.
    – Mark Meuer
    Jun 30, 2017 at 17:41
  • 6
    I think this may be informal in the UK, but in the US 'suck it' is used almost exclusively as an abbreviation of a very vulgar phrase, and would almost certainly not be acceptable. Jun 30, 2017 at 20:56
  • 2
    @kingfrito_5005 In Australia, it's a common expression.
    – Lawrence
    Jun 30, 2017 at 22:16
  • 1
    @MarkMeuer I've added several usage instances where the phrase is used as described.
    – Lawrence
    Jun 30, 2017 at 22:45

One way of explaining the situation, is by saying that the question cannot be answered without first doing a pilot study / feasability study. In this case, the pilot study would obviously include virtually completing the project itself, but it might still be a way of explaining by using terms that are fairly well known.


If you want to be unambiguous, "You can only know [try, know if it will work] by trying it."

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