What does "don't be stupid" imply?

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.

It's hard to escape the short step from "don't be stupid" to "stop being stupid".

No argument will be advanced by implying or stating the other person is stupid (or lying or ignorant).