What do you call this type of argument? [duplicate]
Such an attack is called an ad hominem. It is considered to be a fallacy.
From wikipedia:
Ad hominem (Latin for "to the man" or "to the person"), short for argumentum ad hominem, is where an argument is rebutted by attacking the character, motive, or other attribute of the person making the argument, or persons associated with the argument, rather than attacking the substance of the argument itself.