Impossibility Theorem - Kenneth Arrow
This theory states that there is no possible way for an election to happen that meets the specific criteria of rationality and reasonable democratic values at the same time. Some of the democratic values, which are the dimensions evaluating the electoral process, expected to be met include the following:
- Absence of dictatorship
- Pareto efficiency
- Universality of alternatives
- Independence from irrelevant alternatives
- Impossibility to express false preferences
It is worth noting that this theory assumes that the individual economic agents who are involved are rational.
The theory of social choice leads to the fundamental question: "Under what conditions do the aggregate preferences of a group of individuals become rational while satisfying certain axiological conditions?" This question attempts to find out whether it is possible to develop a social choice function that sums up all individual preferences to come up with a social order that is rational and democratic. In summary, Arrow's theorem concludes that there exists no rule of aggregation or preference that possesses normative properties which are desirable unless a dictator forces these preferences.