In practical matters, this is not quite true. If you ask 'will this program launch a toaster to orbit mars', you can usually answer that question with high con

In practical matters, this is not quite true. If you ask 'will this program launch a toaster to orbit mars', you can usually answer that question with high confidence. The halting problem describes the situations where you can't decide one way or another, but it does not say you can't decide anything. This is a very important distinction. We write code to analyze other code all the type. It's a core part of developer tools. If it was impossible, life would really suck.