Abstract
It is with great delight that I have accepted the unexpected invitation to edit this two part special issue of Foundations of Chemistry dedicated to the philosophical aspects and implications of the quantum theory of atoms in molecules (QTAIM) (Bader 1990). This theory has been primarily the oeuvre of Richard F. W. Bader (1931–2012), one of his most significant (but not the only significant) contributions to chemistry. Bader’s contributions have been summarized in a tribute (Matta et al. 2011) that appeared in a recent Festschrift of The Journal of Physical Chemistry A (2011). This special issue of Foundations is neither a duplication, a complement, or an afterthought to that Festchrift, nor is it intended as another tribute to this great scientist, as deserving as he may be, instead it serves an entirely different purpose. This issue is focused principally on the epistemology and ontology of the science of QTAIM. The sort of questions that are addressed in, or that should emerge from