What we know how to do and what we have done differentiate us from others.


What we know how to do and what we have done differentiates us from others.

Can anyone explain to me which is correct and why?

marked as duplicate by FumbleFingers, Mitch, tchrist, Edwin Ashworth, anongoodnurse Dec 12 '14 at 0:14

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Only nouns have plurals, and differentiate is a verb, so it is never plural.

What you are referring to is the third person 's', which is applied when the subject is he, she, or it:

I walk
you walk
he/she/it walks

In your example, the subject is "What we know how to do and what we have done", which is an it, hence:

What we know how to do and what we have done differentiates us from others

is correct.

  • 1
    I disagree. Depending on exactly how the speaker sees "it" (sorry! :), the things we know how to do and the things we have done might represent two significantly different categories which could reasonably be attached to a plural verb form. And even if there's only one "what", it can still reference multiple things - "What I upvote on ELU are those questions I find interesting". – FumbleFingers Dec 11 '14 at 14:57
  • 1
    ... quite true. Bacon and eggs is my favourite breakfast, but bacon and eggs are both in short supply. – Edwin Ashworth Dec 11 '14 at 15:22
  • @FumbleFingers, I can see how it may be possible to turn the subject into two subjects and call it 'they', but in the absence of a comma or any other device separating them that seems to be stretching it somewhat. To steal Edwin's example "bacon, and eggs, differ from carrots" compared with "bacon and eggs differs from toast and marmalade" – Roaring Fish Dec 11 '14 at 15:37
  • To be honest I find OP's example a bit "odd", since for most purposes in such a context you'd assume things we have done are just a subcategory of things we know how to do (which includes things we haven't got around to doing yet, and those we just don't want to do even though we know how). It would work better for me if we reversed the two sub-elements - which would draw attention to the difference between past achievements and the (potentially much greater) things we might accomplish in the future. And which would encourage me to refer to them in the plural. – FumbleFingers Dec 11 '14 at 15:54
  • I guess if it wasn't odd it wouldn't be a question! Interesting that you say reversing them would make it more of a 'they'. I would need a comma for that. I wonder why? I can see "I am going to buy bacon and eggs" being different to "I am going to buy eggs and bacon", but only because of the sociocultural knowledge of bacon and eggs for breakfast. – Roaring Fish Dec 11 '14 at 16:58

The choice of whether to use the ‘s’ changes the meaning of the sentence. The answer is thus, it depends on what you’re trying to communicate. Do you want to imply that “what we know how to do” and “what we have done” are two different sets of things? Or one and the same?

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