Back when I used to chair meetings with more than 3 people, I liked to start every meeting with what I call the Three Assumptions.

1. The Greater Good Assumption. We assume that each of us is in this meeting to serve the greater good, each motivated to achieve something beyond satisfying our own selfish desires.
2. The Transparency Assumption. Given Assumption 1, since we are all here for the greater good, we therefore assume that none of us has anything to hide. Hence, we assume that each of us is transparent in intention and communication.
3. The Reasonableness Assumption. Given Assumptions 1 and 2, since we are all serving the greater good and have no hidden agenda, we therefore assume that we are always reasonable. Even when we disagree intensely, we are doing so for good and honest reasons.
(And after stating the 3 assumptions, I usually invite all to abide in 30 seconds of silence to generate the conditions for inner calmness).
Of course, none of these assumptions may actually be true. For example, somebody in the room may be a real jerk. But I like the idea of starting a meeting with these assumptions about ourselves and other people around the table. My hope is that starting with positive, altruistic assumptions may actually lead to positive, altruistic behavior.
If you decide to try this at your meetings, please feel free to let me know how it works for you. That includes you, Barack. Yes, and Joe too.