Social choice theory emerged in the 1950s with the research of Kenneth Arrow (1921−2017) and Duncan Black (1908−1991). Arrow's possibility theorem (subsequently called the impossibility theorem) establishes that preference cycles cannot be avoided: a majority of voters prefer candidate A to candidate B, a majority prefer B to C, and a majority prefer C to B (the aggregated preferences are not transitive). This result has often been invoked in political theory to demonstrate the irrationality of democracy: the fact that it may be impossible to establish a collective ranking of preferences is evidence that collective decision-making may be irrational.
On this point, the dissertation shows that Arrow's model is not relevant because it assesses decision rules according to whether preferences are transitive, a criterion that is not relevant to political theory: the multidimensional nature of choice makes it impossible to establish an ordering relation on individual preferences. At either the individual or the collective level, transitive preferences are no guarantee of rationality and should not be used to assess aggregation rules.
Furthermore, various authors have been cast as forerunners of social choice theory: Ramon Llull (1232−1316), Nicholas of Cusa (1401−1464), Jean-Charles de Borda (1733−1799), Nicolas de Condorcet (1743−1794), and Charles Dodgson (better known by his pen name Lewis Carroll, 1832−1898). By reconstructing the intellectual context and the true meaning of their models, the dissertation shows that they were not forerunners at all, but devised models for theories very different from social choice theory, with aims, methods, and conceptions of voting that were sometimes incompatible.
Assessing the quality of voting
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