If you don't hedge your statements about programming, you will invariably be wrong. There are always counter-examples.

The kind of ambiguity and side-effects I'm alluding to are ones programming languages explicitly support and encourage, like overloaded operators and overloaded methods in C++. In C, the effects of a segment of code are comparatively predictable just by looking at the code itself. In quite a large number of languages, you can't draw many conclusions about what a segment of code does without looking in multiple other places.