Cardinal voting systems: Difference between revisions

===Applicability of Arrow's theorem===

[[Arrow's impossibility theorem]] demonstrates the impossibility of designing a set of rules for social decision making that would obey every ‘reasonable’ criterion required by society. Some activists believe that Arrow's theorem only applies to [[ordinal voting]] and not cardinal voting. They point out that that it is technically possible for several cardinal systems to pass all three fairness criteria. The typical example is [[score voting]] but there are also several [[Multi-Member System |multi-winner systems]] which proport to pass all three of Arrow's original criteria. Additionally, there are cardinal systems which do not pass all criteria but this is not due to Arrow's theorem; for example [[Ebert's Method]] fails [[Monotonicity]].

However, subsequent social choice theorists have expanded on Arrow's central insight, and applied his ideas more broadly. For example, the [[Gibbard-Satterthwaite theorem]] (published in 1973) holds that any deterministic process of collective decision making with multiple options will have some level of [[strategic voting]]. As a result of this much of the work of social choice theorists is to find out what types of [[strategic voting]] a system is susceptible to and the level of susceptibility for each. For example [[Single Member system | Single Member systems]] are not susceptible to [[Free riding]].