Linguistic doubt.

[Enrique]

When an American says "I can't touch it" or even "I can't do it", how can the listener tell between "I can't touch it" and "I can touch it", given that they pronounce "can't" with an a like in "can"? Do they rely on context alone? And how can the context be enough in all cases? If I say "stretch your arm an you'll be able to touch it", being answered "I can't touch it", or "I can touch it", I would be receiving an ambiguous message. Should I not?

Of course, an American can always split "can't" into " can not". Perhaps this provides the answer.

[Peter]

Use the British pronunciation - it's quite clear!

[Enrique]

It seems a good advice. It may be that, in American usage, the fact the in affirmative constructions the stress does not fall on 'can' whereas in the negative it does, helps. In 'I can touch it', the stress goes on 'touch'. Compare with "I can't touch it", where the stress falls on 'can'.

[Sorrano]

It seems a good advice. It may be that, in American usage, the fact the in affirmative constructions the stress does not fall on 'can' whereas in the negative it does, helps. In 'I can touch it', the stress goes on 'touch'. Compare with "I can't touch it", where the stress falls on 'can'.

An exception with the "I can touch it" is when the person realizes that he/she actually can touch it, then the stress is on the can, but it should be clear what the meaning is.

[Chris]

It seems a good advice. It may be that, in American usage, the fact the in affirmative constructions the stress does not fall on 'can' whereas in the negative it does, helps. In 'I can touch it', the stress goes on 'touch'. Compare with "I can't touch it", where the stress falls on 'can'.

That is true, and also the vowel sound of the "a" in "can" tends to be different than in "can't". "Can't" seems fully pronounced, with the short "a" exactly as you expect. But "can" tends to come out more like "kin", unless you are emphasizing the word as in Sorrano's example. And in that case, the "n" will flow smoothly into the "t" in "touch", so won't be confused with "can't". Of course, there are a lot of different accents that come with different pronunciations in the U.S., so this may not always apply exactly.

[Enrique]

The subtleties of a language! All this is very interesting. Thanks guys.