added a citation

tex/proposal-phd.tex

@@ -518,6 +518,7 @@ \subsection{Desiderata}
 \paragraph{Reciprocity}
 The desiderata of taxation and deliberation are seemingly in conflict.
 Taxation requires people to consider an exogenously given catalogue of abstractions, and deliberation implies that no such set of arguments can be unconditionally accepted.
+This is a general contradiction of procedural and substantively epistemic formulations of deliberative democracy \cite[402]{Bohman1998}.
 
 This impasse has real repercussions for the proposed research design: apparently, it can serve only one master.
 Either, participants misunderstandings can be revealed by treating them with introductory economics, \emph{or} they can deliberate any which arguments they themselves find comprehensible.