Motley Fool co-founder David Gardner is a big fan of "better." He has built his own career out of helping people invest better, of course, but he's also always on the lookout for people offering us ways to improve our lives in areas beyond the financial. And when a person has ideas in that vein, they frequently choose to share them with the world in the form of a book. Hence his decision to inaugurate an "Authors in August" theme for the Rule Breaker Investing podcast.

For this episode, he's interviewing Priya Parker, founder of Thrive Labs, which specializes in teaching leaders how to transform the way they gather people together. Her book is The Art of Gathering: How We Meet and Why It Matters. In this segment, she flips the script on the platitude "the more the merrier," asserting that an unwillingness to be more exclusionary is diluting and diminishing our gatherings.

A full transcript follows the video.

This video was recorded on Aug. 8, 2018.

David Gardner: All right, Priya. So from thinking hard about purpose, in the very next chapter you tell us to "close doors." To start thinking about who or what we want to exclude from our gatherings. Give us some more intel.

Priya Parker: The age-old adage "the more the merrier" has actually diluted our gatherings. It comes from a spirit of generosity and what I'm arguing is keep, keep, keep the spirit of generosity in your gatherings; but be generous to the people that you want there.

One of the things that I've seen at a lot of gatherings is that we're afraid to exclude people because we're afraid of offending them, and by including them [in part because you want to be polite to the people in the room], the focus of a gathering can get diluted.

My father recently retired. He was a civil servant for 25 years. He retired from a government agency two weeks ago. He called me up to talk about his retirement party that some of his colleagues were planning for him and he said, "You know, there are three other people this month that were also retired. I was thinking maybe I'd invite them to join the retirement party."

Gardner: Very generous.

Parker: And I thought it was a great thought. I said, "Do not do that." I said, "Please do not do that."

He said, "Why? It would be so generous of me. I feel kind of bad. They're planning this for me. What about those people?"

And I said, "Those people should have their own retirement party..."

And I just played it out for him. I said, "Who, then, are you going to invite? What if they invite colleagues that don't know you but know them? Are you going to have a toast for all of you together? Are you going to broadly not do anything that would offend either one of you? You have muddled purposes." And so in that case I was saying exclude well, meaning don't try to honor multiple people at the same retirement party.

But for your guests, the same thing. That closing doors means to choose a radical, disputable purpose and then to ask who will allow this purpose to come true. Another example from the book is a man in the fifties. He's an Egyptian. A graduate student who moved to a small town in Germany. Realized there was no student-run bar -- his name is Osmand Abousteit -- and started a student-run bar. It was kind of cool because the rules were different, then. They served beers out of bottles, which at the time was considered kind of rude. They didn't pour it into a glass. But it was also student-only.

And one day the vice mayor of the town came to the bar. He was not a student and the bodyguard wouldn't let him in. He made a big fuss and then the owner came out [Osmand]. And it was this moment of truth whether he closed the door physically and said to the vice mayor, "You can't come in," or "you can come in." And he held the line and he didn't let the vice mayor come in. And that day that gathering basically put its teeth into its purpose, which is to say this is not just for students. It's also not for not students. And he was willing to destroy value [a local celebrity coming into his establishment] in order to preserve its purpose.

Gardner: That exclusionary mentality, just to broaden it [thinking about the world of business]. How about Southwest Airlines deciding not to charge us for our bags? In a sense that's the same thing going on. They're excluding the opportunity to make money, but they're differentiating themselves and making themselves one of the most valuable airlines of the last 30 years partly through those kinds of radical decisions.

Parker: And it's a radical decision [of] Southwest Airlines in part because it's not a shtick. It's not a marketing play. They know the purpose of their company, they know who they want to fly their company, they know who they want to hire to be on their planes, and they made a decision that charging for bags didn't match that.

Similarly, maybe the competitors then try to compete by also not charging for bags [though Delta and United have not followed suit, unfortunately] and then they wonder why they're not getting the same...

Gardner: Loyalty...

Parker: ... revenue bump as Southwest, and it's because they need to figure out their own purpose and they need to figure out their decision of what they cut or what they charge more for to align with their purpose. If you only copy somebody else's solution it becomes a shtick.

David Gardner has no position in any of the stocks mentioned. The Motley Fool recommends LUV. The Motley Fool has a disclosure policy.