4 ms·

There’s the classic “you can’t add too much water to the reactor” where “can’t” can mean you are physically incapable of adding too much water, and therefore sh

There’s the classic “you can’t add too much water to the reactor” where “can’t” can mean you are physically incapable of adding too much water, and therefore should add a lot, or “can’t” can mean you must not add to much water.

stephen_g 5y ago
Yes, but that’s not so much a problem with the language but more an issue of sentence construction. A big part of good communication in any language is anticipating that sort of ambiguity and adding context or rephrasing to remove it if required. ‘Can’t’ is really too passive to use if it really is ‘must not’ for anything serious, so while the sentence could work either way in spoken communication (because you can convey enough context with tone of voice and emphasis to imply which sense you mean), it would still not be a great choice of words if you mean the second sense.
- casmclas 5y ago
  "Can't" isn't even the slightest bit passive. But a person who is telling others how to communicate well will always use technical terms with the wrong meaning. In this case a negative imperative is what you should be using. Moreover, since it's a life-or-death matter, we need to carefully explain ourselves. "Do not add too much water to the reactor. If you add too much water, the reactor could explode. The reactor should never contain more than 1000 litres of water. If it is overfilled, immediately follow the steps in 3.4.1 to perform an emergency evacuation." By being careful in our follow up, we reduce the risk of any misunderstanding. We cannot prevent a person from misunderstanding, but at least they are more likely to realise they have misunderstood something and seek clarification. "Must not" is reasonably well-understood by native speakers of English, but it is confusing to non-native speakers because even though "must"="have to", the negations have different meanings. It is no use being technically correct if the person whose responsibility it is thinks you said "you don't have to add too much water to the reactor". The prevalence of "must" also varies throughout the native-speaking world.
  - errnesto 5y ago
    Especially in german where “You must not“ reads very similar to “Du musst nicht“ Which means “You don’t have to” “Yo must” could be correctly translated to “Du musst” though...

stephen_g 5y ago

Yes, but that’s not so much a problem with the language but more an issue of sentence construction. A big part of good communication in any language is anticipating that sort of ambiguity and adding context or rephrasing to remove it if required. ‘Can’t’ is really too passive to use if it really is ‘must not’ for anything serious, so while the sentence could work either way in spoken communication (because you can convey enough context with tone of voice and emphasis to imply which sense you mean), it would still not be a great choice of words if you mean the second sense.

casmclas 5y ago
"Can't" isn't even the slightest bit passive. But a person who is telling others how to communicate well will always use technical terms with the wrong meaning. In this case a negative imperative is what you should be using. Moreover, since it's a life-or-death matter, we need to carefully explain ourselves. "Do not add too much water to the reactor. If you add too much water, the reactor could explode. The reactor should never contain more than 1000 litres of water. If it is overfilled, immediately follow the steps in 3.4.1 to perform an emergency evacuation." By being careful in our follow up, we reduce the risk of any misunderstanding. We cannot prevent a person from misunderstanding, but at least they are more likely to realise they have misunderstood something and seek clarification. "Must not" is reasonably well-understood by native speakers of English, but it is confusing to non-native speakers because even though "must"="have to", the negations have different meanings. It is no use being technically correct if the person whose responsibility it is thinks you said "you don't have to add too much water to the reactor". The prevalence of "must" also varies throughout the native-speaking world.
- errnesto 5y ago
  Especially in german where “You must not“ reads very similar to “Du musst nicht“ Which means “You don’t have to” “Yo must” could be correctly translated to “Du musst” though...