Empiricism
From dKosopedia
Empiricism is the the use of empirical data, that is, data collected and compiled from the real world experiences. Modern science is empirical and in fact the whole purpose of experiments is to create experiences which are reproducible so that they can be relied upon, that is, to make the empirical data consistent and universal. This characteristic is now part of the idea of empiricism, scientific empiricism, so empiricism is synonymous with acceptance of scientific method.
It's crucial to understand the idea of theory and the reason that theory is always changing is that the empirical data keeps coming in, and there is a continual process of evaluation as the data is collated, categoried, modelled, explained and reexplained.