Easy and cheap to implement
Since Approval Voting is the same as our current voting system but without a restriction on the number of votes allowed, Approval Voting requires no significant ballot changes or costly upgrades to existing voting machines or tabulation software. In fact, voting for more than one candidate is already used around the country for races such as for multi-winner at-large city council seats. Approval voting would simply apply the same voting rules and tabulation methods to single-winner races.
Instead of being limited to voting for only one candidate, voters can vote for as many candidates as they wish. While some voters will set their approval threshold high and vote for just one or two candidates, others will set their threshold low and vote for all but their most hated candidates. Given the strong environment of negative partisanship, the latter case is fairly common under approval voting.
Removes vote splitting almost entirely, virtually eliminating spoilers
Under normal plurality voting, the more similar two candidates are, the more they split the vote that normally would go to one or the other candidate. This is called vote splitting. Since approval voting allows voters to approve of all candidates that they like, there is no longer any problem with having similar candidates in a race.
You can never get a worse result by voting for your favorite
Regular plurality voting strongly motivates voters to vote strategically for the lesser-of-two-evil major party candidates which boxes out any promising third-party or independent candidates. If you do vote for the lesser-of-two-evils candidate under Approval, there's no reason to not also vote for your favorite. The only way this could hurt your preferred major-party candidate is if your favorite actually wins, which is what you'd want anyway. Most importantly, voting for your favorite will never cause your least favorite to win (favorite betrayal), a classic problem with Ranked-Choice Voting.
Significantly fewer spoiled ballots
Since Approval Voting is literally our current voting system but with fewer rules (vote for only one), it results in fewer spoiled ballots.
Ballots look the same, except the rules indicate that you may vote for any number of candidates
Unlike other alternative voting methods, switching to approval voting requires almost no change to existing ballots. Ballot instructions simply must be updated to read "Choose one or more".
Results are still easy to understand
Since Approval Voting is tabulated using addition in a single round, the results are simply a list of candidates with the number of votes each received. These results are easy to report and easy to understand. This is not the case for some other voting methods like RCV which requires a big table showing intermediate results from any number of rounds. This is more important than ever given recent political unrest in the US, since more transparent election results are more likely to result in higher trust in election outcomes.
Example Ranked-Choice Voting Results
Example Approval Voting Results
Tends to elect candidates who would beat all rivals head-to-head
One common way to determine if a voting method selects the best candidate is whether the winner would have won in a head-to-head race against all other candidates. Since Approval Voting adequately captures secondary support (support for candidates other than a voter's favorite), it tends to elect the most liked candidate over all.
Tends to elect more consensus winners
While plurality voting often elects polarizing candidates with a small plurality of support, approval voting requires candidates to have broad support from the larger electorate to win. This results in elected officials with a greater popular mandate to govern.
Alternate candidates get a more accurate measure of support
Third parties are often written off by donors and the media because their true support is not reflected in choose-only-one polls and election results. Approval Voting allows minor candidates to see true levels of support and thus gain funding and publicity proportional to that true support. In the example below, the green candidate came in a distant 3rd place with only 3.2% of the vote in the plurality election results despite having an astounding 51% approval from voters.
Election Results Using Plurality
Election Results Using Approval
What Do Approval Opponents Say?
Less Expressive Than Other Alternative Methods
Approval only allows voters to express approval or disapproval for each candidate. This is more expressive than plurality, but less expressive than Ranked-Choice Voting or any other scored method (STAR).
Voters May Struggle To Set An Approval Threshold
Voters have to decide for themselves where to set their approval threshold. Should they vote for only one, all but one, or something in between?