I am writing a paper, and I am stuck into this grammar problem:

As has been proven

As was proven

Which one in correct?

  • 2
    It's worth noting that as was proved has always been far more common than the proven version (which sounds rather mock-archaic/dialectal Scottish to me). Commented Feb 20, 2015 at 14:55
  • @FumbleFingers ... or American. (A lot of us say proved, but proven is certainly not unusual.) Commented Feb 22, 2015 at 12:36
  • @Peter: I never thought to check that, but comparing NGrams for contemporary AmE usage and BrE usage does indeed show a clear difference in relative prevalence. Commented Feb 22, 2015 at 13:42

2 Answers 2


Both are correct, but they have slightly different connotations. "has been" places slight emphasis on the fact that a proof exists, while "was" places slight emphasis on the act of proving it. Given the structure of the phrase, I like the former better.

  • It is simply the difference between using the simple past and using the perfect. It is just I was happy versus I have been happy.
    – WS2
    Commented Feb 20, 2015 at 15:32

Understanding the technical time distinction between the two sentences is actually quite useful in practice. The first sentence is set in the present (the present perfect tense) while the second second is set in the past (the simple past tense). Although both sentences may reference the identical past event (that is, the actual proving), each look at this event differently.

The first sentence, set in the present, is concerned with the result of the past's proving, and is unconcerned about when (that is, the time) this event occurred. The second sentence, set in the past, is concerned with the past event itself, and implicitly or explicitly with its time (minute, day, year, century, epoch).

For example,

Last year the mathematician finally proved the theorem. Today, because the theorem has been proved, we can use its results in our experiments.

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