If I'm refuting that everyone in the world knows x, by showing a large population that doesn't know x. Saying that there is some other population that does know

If I'm refuting that everyone in the world knows x, by showing a large population that doesn't know x. Saying that there is some other population that does know x makes no difference. GP: all trucks are red. Me: no, here's some trucks that are blue. You: but look how many red trucks I see over there.