I was in an argument and the other party stated in his last sentence "don't be stupid". Does this statement actually mean that I am stupid and should quit being stupid or what? Is this statement insulting? And is it appropriate in arguments?
The context, in which the phrase has been used, is quite essential - it is always a key to communication. Understanding the background of your conversation in many ways is the answer to your question.
If you say that you've had an argument (we do not know on what topic), I can suppose the following (there may be tons of examples):
E.g. Topic 1 'Let's get drunk and drive/ let's smoke in a train etc.' In this context if you say these words, the phrase 'Don't be stupid!' looks (to my mind) not insulting but dissuasive - as a warning not to do stupid things. (You should understand yourself that you are wrong)
Topic 2 'Let's argue on some particular topic: gender relationship/politics/economy etc' In this context, the phrase 'Don't be stupid!' may be insulting if:
- you are providing the second party with the only one correct answer but the other party won't agree and use the insult as a way to shake you off;
- if you are the second party who provides incorrect answer and gets the phrase 'Don't be stupid!' as an assertion.
So, as you see, there are a lot of examples. I think, it depends highly on you either to get insulted or do not pay attention.
In addition to being a rude remark, it's one of several ways of ending an argument by attacking the person who disagrees with you. In your example I wouldn't call it a fallacy but it comes near an "ad hominem" where, having no convincing reply, you attack the source of the argument so as to invalidate it.
I went to a Tesco supermarket in England with my winning Lottery Ticket to claim my money. The cashier just looked at it, ripped it and threw into a Bin saying, 'It is not a Winner'. I told her I knew it was a Winner since I Matched certain numbers required to win a prize. She retorted: 'Don't be stupid' and walked away. When I complained to her Manager, he said the words were not insulting - claiming I did not understand English (I was a foreigner to England from an African Country where English is the official business language). Some customers in the Store supported the Manager that there was no insult. I was alone on my side, I walked out of the Store crestfallen. In the context of her answer and the situation, she obviously had implied that I was stupid, which in this case I was not.
In England, "don't be stupid" seems to be an innocuous expression of disagreement. In the U.S., it is a rude insult likely to elicit an aggressive verbal or even physical rejoinder ("Who you calling stupid, dumbass?"). Certainly in the U.S., a store clerk saying this to a customer would be fired.
It is contextual...
Don't be stupid, when used colloquially is often meant to be endearing. "Don't be stupid, I'll cook for you right away." "Don't be stupid, I can drop you to office" It's prefixed here to emphasise the ease and the effortlessness by which the other is willing to do something for you. "Don't be stupid, of course I love you."