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What is the difference in usage between ability and capability?

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On my side, I think these two words are synonyms, since they have the same sense. –  Fadhili Jul 1 at 17:50

4 Answers 4

up vote 11 down vote accepted

Capability implies unrealised potential, as in "John is capable of winning", which implies John has the ability to win but it's not definite. It means more or less "John has the talent that's needed to win."

Ability, on the other hand, implies possibility. "John is able to win" means John is in the running to win but not necessarily that he has the skills or ability to win. It means more or less "It's possible that John will win".

But here's where it gets more confusing:

"John is able to read" means John can read without doubt, whereas "John is capable of reading" means John has all the necessary brain power and whatnot to be able to read but the question of whether or not he can read at the moment is left unsaid (although the fact that someone does say "John is capable of reading" probably means John can't read right now).

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I disagree. "John is capable of reading" does not imply that John can't read at the moment. –  Alan Hogue Aug 6 '10 at 0:05
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The "cap-" on "capable" comes from the latin "capere," to grasp or take. So "John is capable of reading" does mean more accurately "John is able to learn to read" or rather "John is able to grasp the skill of reading," not, however, that he IS able to read. –  kitukwfyer Aug 6 '10 at 0:25
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The etymology of a word does not necessarily have anything to do with its modern meaning. Again, saying that someone is capable of x does not imply that they cannot do x right now. That is simply false. –  Alan Hogue Aug 6 '10 at 0:49
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Another good example might be: all nations at the World Cup are able to win (in the sense that it's possible), while only a few are realistically capable of winning (i.e. have the necessary skills to do so). Alternatively: Kobe Bryant is able to slam dunk a basketball, while John, my very tall friend, is capable of slam dunking a basketball (which implies he can't slam dunk a basketball at the moment). –  Sarhanis Aug 6 '10 at 3:35
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Let's try something like this. (1) John is capable of reading, but he is currently illiterate. (2) John is able to read, but he is currently illiterate How do those sound to people? I think the distinction is very subtle and not a matter of denotation... –  Alan Hogue Aug 6 '10 at 9:52

If we would like to describe the functionality of a specific product like a software, I think it is more common to use 'capabilities' (vs 'abilities'): "MS Word has these capabilities: edit tables, copy and past, styles etc."

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There are some interesting answers to this question. My understanding of the two words is that "capability" implies having the tools or physical attributes to perform a task while "ability" implies having the skills or training to perform a task. I think this means that my usage coincides with Sarhanis' description and not Alan Hogue's. It also means that you are correct: software has capabilities, not abilities. –  chimp Feb 2 '11 at 8:21
    
+1 good usage ! –  igor Feb 2 '11 at 8:32

There's another shade of meaning not yet touched upon. able can also be of things, "of a thing (esp. a boat): strong, substantial, well built; or a person who is intelligent, skillful, apt, talented, or clever (OED). Compare, "It is an able ship/It is a capable ship." They are both meaningful, but I would be more likely to use the first one. Another example, "She is an able tour guide/she is a capable tour guide". The second sounds contrived to me, even a little damning.

It's also interesting to note that they entered English through different sources, and that able is the older of the two.

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I don't understand the downvote here, (now balanced with an up.) @Charlie's comments ring true to this native (US) speaker. –  DWin Jul 5 '12 at 23:45

As far as I can tell, these are very nearly perfect synonyms.

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interesting point, I've always thought of them as being distinctively different and used them in differing contexts. But the more I think about it the more I probably could be switching each for the other. –  Anonymous Type Oct 27 '10 at 21:35

protected by tchrist Jul 1 at 18:14

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