Why someone would abstain: My father-in-law is on the zoning board in our town and an important vote came up last month. He abstained because he felt neither side had proven its case and convinced him to vote either way. Probably a sligtly different case than a PTO vote, but it is one example.
There's a subtle difference here that Mum highlighted: do your bylaws require 2/3 approval of members IN ATTENDANCE or 2/3 approval of ALL VOTES CAST? If it's based on the members in attendance, then the abstentions negate the yea votes. If it's based on total votes cast, the abstentions don't count, so you'll calculate the results based only on actual yea/nay votes.
Since your bylaws don't speak to this issue, I again went looking for a recommendation in RRO. My book says that majority is more than half of the VOTES CAST by legal voters. It's an oxymoron to refer to an abstention as a vote, so RRO means you calcuate majority (or 2/3) based only on the actual yea/nay ballots cast.
Of course, like Mum pointed out above, a group's bylaws could specify that majority (or 2/3) is calculated based on the number of members present, superceding RRO. But since your bylaws don't say anything, typically that means you defer to RRO (that's why you usually see a statement in bylaws declaring Robert's Rules of Order as the group's parlimentary authority.)
Thanks, Mum, for the RRO link. I haven't been there before. good stuff.
Another question that we haven't addressed: why will people want to abstain on this important issue?
An abstention is not a "nay." But, it can have the same effect as a nay vote if you need a majority to vote "yes" on something. For example, if you have 30 people eligible to vote, and you require 2/3, or 20, to vote "yes" to get something passed, all the abstentions are effectively "nays." Because if you have 15 vote yes, 5 vote no, and 10 abstentions, you don't have your 2/3, even though only 5 said "nay." You can also go here (question #6) www.robertsrules.com/faq.html#6
for more info.
Robert's Rules of Order is the definitive source for the answer. From a summary book, Robert's Rules of Order by D. Patnode, "With the right to vote comes the right to abstain from voting, but the chair should never call for abstentions, nor do members have the right to announce that they have abstained. Abstentions have no effect on calculations of votes. (When a ballot is marked "abstain" it is considered a blank."
My understanding is that obstaining is not counted with either a nay or yes vote, it is counted by itself. "4 voted yes, 3 voted no, and 2 obstained"--something like that. But I can tell you that obstaining is often looked upon informally as a no vote even though it is not counted that way.
