For us, differences between people are the noise. We have to somehow pick the signal out of that, and the method is a way of doing it. Facts and organizing principles. They're permanent, and they're the basic information for science. It doesn't matter what your world view is, you have to explain the same set of information.
Examples are things like the speed of light, the capacity of short term memory, etc.
They're an overarching explanation that takes all of the facts into account. This is their most important function. It's what makes them useful. Theories are not permanent. The facts they explain are permanent, but the explanations might change in the light of new facts or simpler explanations.