Timeline for What is the difference between "can't" and "mustn't" in the expressing of prohibition?
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9 events
| when toggle format | what | by | license | comment | |
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| May 12, 2021 at 16:33 | comment | added | Lambie | Unambiguous (just for those who are picky): The law prohibits the use of cell phones while driving. Ergo, I mustn't use. Ergo, I can't use it. | |
| Jun 12, 2013 at 7:09 | comment | added | Mari-Lou A | @AndrewLazarus I did say that can is used for possibility, ability AND for permission. "Can" is ambiguous and explains why non-native speakers at the beginning do get confused. In your legitimate example, "Can I park here?" put in a different context, you might be asking for permission. You are in a foreign country and you do not understand the signs so you ask in order to be sure. In your context you were referring to your ability as a motorist. | |
| Jun 11, 2013 at 6:20 | comment | added | Andrew Lazarus | @Mari-LouA, Sure, usually. But I have been known to ask my passengers "Can I park there?" in the sense of "Can I maneuver the car into that small space?" The passengers can see that it is a permitted parking place, and they understand that I am referring to my skills, not permission. (I'm not great at parking a car.) The point of my comment is that words like can, must, and shall often take on a more specific meaning in regulatory or legal contexts. I am not sure if you disagree. | |
| Jun 11, 2013 at 5:37 | comment | added | Mari-Lou A | The OP question contains the pronoun I not the pronoun, it. It is perfectly correct to use either mustn't or can't in the phrase, hence the question is flawed. In traffic laws the more usual terms are: "It is forbidden to use mobiles while driving", or "The use of mobiles is not allowed while driving", or more simply: "It is against the law to use a mobile etc." Must and must not can be seen on notices but they are issued by the authority in charge. "You must not speak during the exam" are instructions written by a school or by an examining board. | |
| Jun 11, 2013 at 5:24 | comment | added | Mari-Lou A | @AndrewLazarus Can has different meanings; ability, possibility and permission. How would you define the meaning of: "Can I park here?" You could interpret in all 3 manners but normally you would be asking if parking was allowed. The same reasoning applies to the negative form:"I can't park here". Therefore it is common to hear and read: "I can't use my mobile here." | |
| Jun 10, 2013 at 16:27 | comment | added | Andrew Lazarus | In some contexts, can and can not refer to physical impossibility, while must not and may not refer to unacceptable acts. Colloquially can not is used for this, too. But the traffic laws will use phrasing like "must not use a cellphone", not "can not use a cellphone". | |
| Jun 10, 2013 at 15:20 | comment | added | Mari-Lou A | -1 Mustn't isn't the only possible answer to the question, you contradicted yourself when you claim that "can" is used in colloquial speech, ( which is true) so what's to stop it from being written? | |
| Jun 15, 2011 at 13:00 | comment | added | Ben Voigt | Notice the lack of parallelism here: cannot = "not possible to do", may not = "not permitted to do", need not = "not required to do", but must not = "required to not do". | |
| Jun 15, 2011 at 0:46 | history | answered | Hunter Spink | CC BY-SA 3.0 |