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That is, after a successful proof of concept would you say "the concept was proved" or "the concept was successfully proofed".

I'm thinking the latter based on the definition of to proof as "to test; examine for flaws, errors, etc." and because proved implies a higher standard (truth); however, proved (or proven) sounds better and to prove has a similarly applicable alternate definition: "to give demonstration of by action."

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up vote 6 down vote accepted

It's certainly true that a "proof of concept" will not necessarily prove the concept. The test may fail. But that fact is hardly unique to this particular use of the word "proof". If you say, "I am looking for proof that the Polynesians discovered America", you may or may not find such proof. Etc etc.

When a proof of concept test is completed, if it was successful the concept is "proven" or "proved". If the proof of concept test failed, then the idea is either "disproven" -- we proved that it doesn't work -- or "unproven" -- the results were not adequate to say it whether it will work or not.

"Proof" as a verb is generally understood to refer to examination of text for errors, as in "The editor proofed the manuscript." I don't think I've ever heard someone say, "The engineer proofed the airplane's wings" or "The accountants proofed the tax software". Certainly not, "The physicist proofed his cold fusion theory." The verb "proof" has very little to do with the noun "proof".

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I believe that in usages such as "The editor proofed the manuscript", proofed is shorthand for proofread. – Marthaª Jan 11 '12 at 17:40
"The engineer proofed the airplane's wings" sounds to me as if he's applying some sort of protective coating. – z7sg Ѫ Jan 11 '12 at 19:57
Thanks. Of all the fine answers, this is the most convincing. – xan Jan 11 '12 at 21:24
@Martha: Maybe so. I'm not aware of any difference in meaning between "proofing a manuscript" and "proofreading a manuscript". – Jay Jan 11 '12 at 21:34
-1 'proof of concept' cannot be broken without losing the significant implication of the integral term. – Kris Jan 12 '12 at 12:44

When you have demonstrated a successful proof of a concept, it has been proved. After all, one of the definitions of prove is demonstrate the truth or existence of (something) by evidence or argument, as in the concept is difficult to prove.

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Prove-as-in-test really only survives in stock phrases such as the exception that proves the rule : proof of concept seems too recent to have that meaning.

It's really a fixed, standalone phrase now, so I would avoid inflecting it : I'd just say a successful proof of concept has been completed.

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I agree with the first part but for the second, I don't see a difference from proof of identity and we do say things like prove your identity. – z7sg Ѫ Jan 11 '12 at 16:38
+1 important distinction and valid point. – Kris Jan 12 '12 at 12:42

The meaning of a proof of concept is not so much to test or examine an idea or technique for flaws as it is to persuade by demonstration that an idea or technique is useful.¹ So, given the choice, "prove" is better.

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IMHO would describe the end game of a proof of [a] concept as a proven or disproved concept.

A proofed concept sounds like a concept which has received some previous justification and is not a concept under test; a dogma

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He proved. It has been proven. – Plastic Sturgeon Jan 11 '12 at 20:11

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