Why am I so sure I’m right when I only see part of it?

In Ud 6.4, ascetics and wanderers of many different religions in Sāvatthī are at war over their views: the cosmos is eternal, or it is not; the soul is the body, or it is something else. Each calls their own view the only truth and the rest foolish, and they wound one another with sharp words. When the monks tell the Buddha, he tells a story. A king once had every person blind from birth in the city brought together, and had an elephant shown to them, one part to each group. Afterwards he asked them what an elephant is like. Those who had been shown the head said it was like a pot. Those shown the ear said a winnowing fan. The leg was a pillar, the tip of the tail a broom. Each group insisted on its own answer until they came to blows. The quarrelling wanderers, the Buddha says, are like that: they do not know what is helpful or what is true, so they quarrel. His closing verse calls them people who see only one part, and who cling to it.