We can make an epistemological approach to politics in the identification of two kinds of political currency: markers and actions. And then we can apply monetary economics to the information that qualifies voting on behalf of political actors.
First we model voting at the legislature as the expenditure of marker or action money. The marker is a cynical vote, and the action is a courageous vote. Cynical is a vote against one's stated principles, and courageous is a vote in favor of one's stated principles.
Given such a model, we can apply essential monetary theory to the two kinds of currency. From the metaphor "bad drives out good" we recall the principal that less valuable money will displace more valuable money in ordinary transaction markets. As the marker currency is valued against an uncertain future (e.g. the actor may never benefit), and the action currency is a foregone conclusion (i.e. historical fact), we can deduce that the marker currency is less valuable than the action currency.
The remaining questions of interest concern the qualifying of voting and the tracking of currency in the real world.
Resolving the model to a practical application may involve conveniences or development. For example, are marker and action transactions at vote casting time both positively signed? Are additional, related transactions necessary to comprehensive information?
An open database of stated positions (courage) is available from Vote Smart.