We're full of seemingly weird cognitive biases: Roll a roulette wheel in front of people before asking them the percentage of African counties are in the UN, their answers correlate with the number on the wheel.
Most of us judge logical strengths of arguments by how believable the conclusion is; by repetition; by rhyme; and worse, knowledge of cognitive biases doesn't help as we tend to use that knowledge to dismiss conclusions we don't like rather than to test our own.