Cumulative Voting - Pros and Cons
Pros
Expressive: The fractional ballot allows more expressiveness than an approval ballot, since the voter can express the degree of approval for each candidate. It also allows more expressiveness than a preference ballot since a voter can express the degree to which one candidate is favored over another and can also express indifference by offering equal fractions to two candidates.
Allows voters to express approval, preference, and indifference more than any other voting system
Cons
Requires voters to understand how to work with fractions which can create inequity for those who do not know how to.
It is much more complex than other voting methods. One reason being that voters may not know what fractions accurately represent their true preferences.
It is susceptible to strategic voting:
If a voters preference is candidate A to candidate B to candidate C they might give all their votes to candidate A who they think has support and could win.
If the voter thinks A, their preferred candidate, has little support they might strategically vote for B, their next preferred candidate, to prevent C, their least preferred candidate from winning the election.
To express that candidate C is their least favorite least candidate, they might split their votes between candidate A and B
Or if the voter wants to support both A and B, but express that their strongest preference is A they might vote for A and B, but give A most of their votes
In conclusion, Cumulative voting is undesirable because it allows voters to express themselves dishonestly and gives the voter so much freedom to vote that their decision making process can be very complex.