In executive meetings of a club I belong to, we follow robert's rules of order. That requires someone to second a motion. But considering that the group is small (5 people), one motions that we end the meeting, someone seconds, and "all in favor" would be the other 3 people. I find the "seconding" step completely unnecessary in such small groups, we could just have someone motion and go straight to "all in favor". So I was wondering, why does it exist in the first place? What is the rationale behind that step that justifies it? I'm guessing it's suitable for large groups, but still when I search about Robert's Rules on the internet, I just get the rules themselves, I don't get any explanation why they are the way they are.
As for 'seconded', per wikipedia:
The purpose of requiring a second is to prevent time being wasted by the assembly's having to dispose of a motion that only one person wants to see introduced
As for why it's in Robert's Rules:
The procedures prescribed by the book were loosely modeled after those used in the United States House of Representatives, with such adaptations as Robert saw fit for use in ordinary societies. The author's interest in parliamentary procedure began in 1863 when he was chosen to preside over a church meeting and, although he accepted the task, felt that he did not have the necessary knowledge of proper procedure.
In summary, Robert's rules are the way they are because that's the way Robert put them together. The reason for seconding a motion is to avoid wasting time by the parliamentary body--as it's a lot easier to ask for a 'seconded' first rather than jumping to a full vote when not needed. A body of only 5 likely isn't as worried about that. The difference between seconding and a full vote in that case may very well be negligible.
I agree with DA's answer. Let me just add some commentary.
The point of Robert's Rules is supposed to be to carry out the will of the majority, while at the same time protecting the rights of the minority.
So for example, consider the motion to close debate. On the one hand, we want to give the minority a chance to present their case and maybe change some minds. But if debate didn't end until no one had anything further to say, then a minority could prevent a vote by just hashing over the same arguments over and over, until the majority gives in from exhaustion or their term of office expires. (In the U.S. Senate, where a vote to close debate requires 60 votes out of 100 but passing a law requires only 51, senators will sometimes drag ou debate as a political tactic. There have been cases of a senator reading a phone book or an encyclopedia as part of a "debate".)
So the idea of a requirement for a second I that, if there aren't at least 2 people who favor this motion at the start, the chance that you will convince a majority to vote for it is remote, so there's no point wasting further time. There have been plenty of cases in small debating bodies where someone will say, "I have serious doubt about this motion, but I'm going to second it to get it on the floor and give Bob a chance to present his arguments for it."
I suppose in a committee of five, requiring a second for a motion to adjourn accomplishes little. Organizations often have by-laws that say, "We follow Robert's Rules of Order except ..." and then give exceptions that work for them.