Can anyone tell me if there is any difference in meaning between the use of "be able to" and the use of "can" ?
In the following pair of sentences it seems that they are similar in meaning:
Scientists are able to explore new planets.
Scientists can explore new planets.
But what about the following pair:
Are you able to help me with my homework? (seems to me that this sentence should be used in a situation in which I am not sure that the person I'm addressing has the knowledge to help me )
Can you help me with my homework? (and this one is more likely to be used in a situation in which I know that the person I'm addressing has the knowledge to help me but I'm not sure he is free right now to do so.)
Waiting for your enlightening answers
www.m-w.com , the second defintion of can is "be physically or mentally able to." To my thinking, that makes "He can" and "He is able to" completely synonymous.
If you said "Do you have the ability to help me?" (regardless of my desire or availability to do it just then) then certainly that's different than "Can you..." which could include whether I have the time to do it.
I'm sure others will have their own interpretation, but that's my two cents.
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2. Can you help me with my homework?
I can do it = PERMISSION – human authority / rules and regulations allow me to do it.
I can do it = POSSIBILITY – external circumstances allow me to do it.
I can do it= ABILITY - inherent properties allow me to do it.
(There are times when these meanings overlap.)
Can you help me with my homework?
PERMISSION: will mum, teacher, the examiner allow it?
POSSIBILITY: if you don't have anything else to do.
ABILITY: are you clever enough/have you got knowledge of the subject
The thing to ask is whether be able to also have the same meanings:
Are you able to help me with my homework?
PERMISSION: will mum, teacher, the examiner allow it? (Seems to be OK)
POSSIBILITY: if you don't have anything else to do. (Seems to be OK)
ABILITY: are you clever enough/have you got knowledge of the subject? (Seems to be OK)
So, up to now, it seems as if both convey the same meanings.
Coates (1983:93) states that in cases of very strong implied actuality (fact), be able to is normally preferred.
EG: "Most people worked harder than me during the University, of course, and when it came to the exams, they were able to draw not just upon two weeks of knowledge. They were able to draw upon three years of knowledge".
Now, why should that be? Does be able to carry less modality, and therefore more sense of actuality, than can in such contexts?
Let's look at this quote from Coates: 2) Be able to is preferred in the present, if actuality is implied: “...and yet you are able to look at the future of it in this very objective way”.
So, as your sentences/questions are in the present form, maybe the to be able to version expresses more of a sense of actuality than it does modality.
She also claims that can is compatible with subjects that are animate or abstract, where able to is not:
*This is able to be done.
This can be done.
*This fact is able to disprove their hypothesis.
This fact is can disprove their hypothesis.
I ran fast, so I was able to catch the bus.
I ran fast so I could catch the bus.
CalifJimI think it's worth mentioning in this thread that the following do not mean the same thing.Please let me know the difference between the two sentences.
People are waiting to help.
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