We owe an initial formal specification to Pitkin, who—despite misgivings about formalizations—observed that democratic responsiveness includes, in one way or another, (a) authorization of a representative by those who would be represented, and (b) accountability of the representative to those represented. Building on Pitkin, D. Castiglione & M.E. Warren (unpublished manuscript; see also Rehfeld 2006) characterize these relationships as follows: