Ethics is a field in which the gap between words and actions looms large. Game theory and the empirical methods it inspires look at behavior instead of the lip service people sometimes pay to norms. We believe that this special issue comprises several illustrations of the fruitful application of...

The Government of Colombia imposes a variety of taxes that must be paid by individual wage earners, called in their entirety "social protection contributions". Since 2007 individual payments have been collected using an on-line mechanism. In order to improve compliance, the Government used a...