t's easy: I've learned over the years that people who believe in certainty, especially those who believe that they can communicate certainty, are dangerous.
Something goes deeply wrong when people assume that it is possible to know things precisely, to name things precisely, and to communicate things precisely. (I'll grant that claims of precision are slightly less dangerous than claims of accuracy.)
I sometimes call it naive positivism, but there are other philosophical schools that lead to the same sad place. Computers, of course, encourage such delusions, but that is largely because they know so little about the world.
Uche is extra-right about URIs, of course, a corner that painfully demonstrates these limitations again and again.