You may find this enlightening: Not only do nontrivial programs sometimes have unevaluated ways that will prevent their termination, but it's been proven that there cannot be a deterministic way to prove that a program will or will not terminate.

The Turing halting problem (will a given program terminate), and Godel's Incompleteness Theorems (nontrivial axiomatic systems can make true statements that cannot be proven), are connected -- each implies the other. And both have been shown to be more than educated guesses about reality.