 First, reductionists can argue that there are no principled reasons that chemical phenomena have not been derived from quantum mechanics. The problem is a lack of computational power and appropriate approximation schemes, not anything fundamental. Schwarz (2007) has made this argument against Scerri, claiming that the electronic structure of atoms, and hence the Periodic Table, is in principle derivable from quantum mechanics. He believes that quantum chemistry’s inability to reduce chemical properties is simply a manifestation of the problems shared by all of the computationally complex sciences. Debate then turns to the plausibility of such “reducibility in principle” claims.