View source for Later-no-harm criterion

{{Wikipedia}}<h4 class=left>Statement of Criterion</h4>

<p><em>Adding a preference to a ballot must not decrease the probability of election of any candidate ranked above the new preference.</em></p>

<h4 class=left>Complying Methods</h4>

<p>'''Later-no-harm''' is satisfied by [[IRV|Instant Runoff Voting]], [[Minmax|Minmax(pairwise opposition)]], and Douglas Woodall's [[Descending Solid Coalitions]] method. It is trivially satisfied by  [[Plurality voting|First-Preference Plurality]] and [[Random Ballot]], since those methods do not usually regard lower preferences. Virtually every other method fails this criterion.</p>

<h4 class=left>Commentary</h4>

'''Later-no-harm''' guarantees that the method will not use a voter's lower preferences to elect a candidate who that voter likes less than the candidate that would have been elected if this voter had kept his lower preferences a secret.

As a result, voters may feel free to vote their complete ranking of the candidates, which in turn may give the election method more complete information to use to find a winner.

'''Later-no-harm''' is incompatible with the [[Condorcet Criterion|Condorcet criterion]].

[[Category:Voting system criteria]]