Economic theory as a means for converting a concept into a project. The case of basic income as an “universal tax credit”[La théorie économique comme outil de conversion d’une idée en projet. Le cas du revenu de base comme « crédit d’impôt universel »]

Debates among Liberals on social justice have played a major role in current discussion on basic income (or universal benefit). In particular, the content of Rawls' "difference principle" has generated the "surfers in Malibu" debate, where Van Parijs can have defended the unconditional nature of basic income. The discussion then has to be moved from philosophy to economics of basic income, which supposes to show that it can be a precise variant of negative income tax. At this point, a rereading of Friedman's intuition on this topic results in seeing basic income as a "universal tax credit". This case study sketches the essential role of economic theory (more precisely, the role of a theory combining taxation and redistribution), so as to convert a concept, which is mainly of philosophical origin, into a viable project, which might eventually be applied.