You might imagine creatures incapable of pretentiousness, but I’m not sure they’d be human. Such creatures would have sex, and eat, and breathe, and build houses, and fight, and raise children but they would never use language to promise more than they could deliver. If they were chasing a lion they’d never say “Hey! I know we can do this!” They would say “Hey! I don’t know if I can do this!”.
You might imagine such creatures, but I don’t know if they would be human, at least not like we are humans. We humans are always aspiring. “I’m going to get that lion — come on!” “I’m going to be a good father — marry me!” “I’m not afraid” “That plan seems good to me!” they all promise more than we can be strictly speaking certain of delivering.
When our friends are aspiring or we are aspiring we call that aspiring, but when our enemies doing it or people we don’t trust we call it pretention or bullshit. He says he’s going to be a good father, but he’s a bullshitter. How does he know? The last lion got away. How can he say he’s going to catch this one?
When you live in a community of the pretentious sometimes you will employ irony. The ironist promises more than he can deliver but he’s actually making a coded point. “I’m going to catch ten lions!”. What does it mean? It means “Look I can say something just like Mr. Lion Hunter. It doesn’t mean you should believe me. So it doesn’t mean you should believe him either.”
Can you lie about being ironic? Yes. The so-called “alt-right” –actually Nazis — pretend they are kidding about being genocidal racists. They aren’t.
Can you be pretentiously unpretentious? Absolutely. You can say “Far be it from me to chase a lion successfully — I’m just a humble bark-dye-refiner. But I would be the best husband you’ve ever met!” The unpretentiousness on topic A is a mask to cover the pretentiousness on topic B.
People sometimes say there is too much irony, and people almost often say there is too much pretentiousness. Maybe yes, maybe no. Anybody can decry pretentiousness and a lot of people can decry irony. But to be pretentious (fine, aspirational) and ironic at the right time, in the right way, to the right degree, about the right thing — that is not so common!