Common factors and causal networks

The target article touches upon some of the most difficult and essential questions in personality psychology. Questioning the notion of a common factor as an as-yet-unobserved common cause of a behaviour domain's exemplars, the authors propose using graphical representations to inspire hypotheses of more complex causal structures. I do not find the case for the de-emphasis of the common factor model to be compelling for those behaviour domains (cognitive abilities) with which I am most familiar. It behoves all personality psychologists, however, to question the foundations of their favoured tools.