If psychology is the science of “mind” and physics is the science of “matter”, then human factors is the science of “what matters”. This claim is more than a simple observation about the scope of human factors (i.e., that it's scope overlaps both with psychology and physics). Rather, I will argue that the science of “what matters” requires an entirely different ontology than those which have traditionally provided the basis for psychology and physics. Two constructs will be central in the ontology of “what matters” - affordance and information.