cannot vs must not

[Allen165]

I've noticed that sometimes the verb "cannot" is used to mean "must not" in English. Here's an example:

"We've got to find some kind of resolve to come away with a win in these situations," Suns coach Alvin Gentry said ."It just really got away from us. We gave up 70 points in the second half and obviously you can't do that."

I think it's obvious that he meant to say "must not." This is only done in informal English, if I'm not mistaken. In formal English one would have to say "must not." Correct?

Your thoughts on this?

Thanks for the feedback.

 

[jamiep]

I think it's a bit more subtle and has an implied meaning something like "If you give up the 70 points you can't expect a favourable result".

 

[Abstract Idea]

"We've got to find some kind of resolve to come away with a win in these situations," Suns coach Alvin Gentry said ."It just really got away from us. We gave up 70 points in the second half and obviously you can't do that."

I think it's obvious that he meant to say "must not."

I don't think "it's obvious he meant 'must not,'" and I think that here if you write mustn't instead of can't the meaning will be different. I agree with jamiep's interpretation.

If you use mustn't the "implied if" pointed out by jamiep is not implied.

 

[euncu]

I don't think "it's obvious he meant 'must not,'" and I think that here if you write mustn't instead of can't the meaning will be different.

Maybe we should be more open when thinking about this question. What if I tell someone "You can't go there", which one of the options below do I really mean?

Being able to:
You can't go there, 'cos you don't have any legs
You can't go there, 'cos you don't have a car
You can't go there, 'cos the road is blocked
You can't go there, 'cos the bridge has collapsed

Suggestion,warning:
You can't go there, 'cos that place is very dangerous for you
You can't go there, 'cos the last you did, you got your wallet stolen

Along the lines of the usage that jasmin165 suggested:
You can't go there, 'cos I don't want you to go
You can't go there, 'cos I need you right beside me

 

[Abstract Idea]

Maybe we should be more open when thinking about this question. What if I tell someone "You can't go there", which one of the options below do I really mean?

Being able to:
You can't go there, 'cos you don't have any legs
You can't go there, 'cos you don't have a car
You can't go there, 'cos the road is blocked
You can't go there, 'cos the bridge has collapsed

Suggestion,warning:
You can't go there, 'cos that place is very dangerous for you
You can't go there, 'cos the last you did, you got your wallet stolen

Along the lines of the usage that jasmin165 suggested:
You can't go there, 'cos I don't want you to go
You can't go there, 'cos I need you right beside me

OK euncu, you changed the subject a little bit. Let us discuss it here.
I guess any of the options you gave above could be a correct interpretation for "you can't go there." All of them are correct. Of course it just depends on the CONTEXT.
In Jamsim165's context, I guess "can't" and "mustn't" have different meanings.

In none of your examples I think one could substitute "can't" by "mustn't", with the very same meaning - even in the last ones.

PS Not a native speaker

 

[euncu]

OK euncu, you changed the subject a little bit. Let us discuss it here.
I guess any of the options you gave above could be a correct interpretation for "you can't go there." All of them are correct. Of course it just depends on the CONTEXT.
In Jamsim165's context, I guess "can't" and "mustn't" have different meanings.

In none of your examples I think one could substitute "can't" by "mustn't", with the very same meaning - even in the last ones.

PS Not a native speaker

Well, what I suggested was not about substituting "mustn't" for "can't". Just what I meant was "can't" could be used in a broader sense to express more than just abilities, possibilities. Yes, I admit that what I'd said changed the subject to some degree, because in the example Jasmin165 gave, the things that the coach said may be interpreted in different ways as the ones below;

We shouldn't have played this bad,
My player had no right to play this bad
or
The score margin was so high that we just couldn't catch up.

 

[fablues]

(Not a teacher)

I agree with Jamiep!
I think the sentence "and obviously you can't do that" means something like: you can't ... treat yourself to ... indulge yourself .. giving up 70 points.