Is there a word to describe a person who habitually expresses strong opinions on a subject without having any facts or background knowledge to base their opinion on. Examples include many politicians, the media when they don’t do research, and many loud opinionated people who “Like the sound of their own voice”. With so many words in our language with very specific meanings it seems a single word to describe this [commonly occurring] situation would useful?
I think you need two words to capture the contradiction inherent in the type of person you describe. So, given that, how about arrogant ignoramus?
Arrogant (M-W): exaggerating or disposed to exaggerate one's own worth or importance often by an overbearing manner
Ignoramus (M-W): an utterly ignorant person
I also like SteveSliva's suggestion of uninformed blowhard, which is in the same vein as arrogant ignoramus.