 Other cases, however, are less clear-cut. For example, suppose that a second trained meteorologist evaluates the available meteorological data E and arrives at her own view about the possibility that it will rain tomorrow. She then learns that the first meteorologist arrived at the view that it will rain tomorrow on the basis of evidence E. Should the second meteorologist count her colleague's opinion as additional evidence for the hypothesis that it will rain tomorrow? Or would doing so be in effect to engage in a kind of illegitimate double counting of the original evidence (Kelly 2005, Matheson 2009)? More generally, in what circumstances, exactly, is evidence of evidence (for some proposition) evidence for that proposition (Fitelson 2012, Feldman 2014)? Questions about the nature and bearing of higher-order evidence are topics of active research.