# Pareto criterion

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The **Pareto criterion** is a basic criterion for evaluating voting systems. It can be defined in this way:

If every voter ranks candidate

Aabove candidateB, thenBmust not be elected.

This criterion is important in the context of Arrow's impossibility theorem.

Virtually every devised election method satisfies this criterion. An example of a method which would fail it would be *Random Candidate*, where some candidate is elected at random, regardless of the submitted votes.