Interdisciplinary communication, and thus the rate of progress in scholarly understanding, would be greatly enhanced if scholars had access to a universal classification of documents or ideas not grounded in particular disciplines or cultures. Such a classification is feasible if complex concepts can be understood as some combination of more basic concepts. There appear to be five main types of concept theory in the philosophical literature. Each provides some support for the idea of breaking complex into basic concepts that can be understood across disciplines or cultures, but each has detractors. None of these criticisms represents a substantive obstacle to breaking complex concepts into basic concepts within information science. Can we take the subject entries in existing universal but discipline-based classifications, and break these into a set of more basic concepts that can be applied across disciplinary classes? The author performs this sort of analysis for Dewey classes 300 to 339.9. This analysis will serve to identify the sort of ‘basic concepts’ that would lie at the heart of a truly universal classification. There are two key types of basic concept: the things we study (individuals, rocks, trees), and the relationships among these (talking, moving, paying).