We all have an individual consciousness (IC) that is a state of awareness even if most of the time we behave in our life on an auto pilot mode with our mind wandering around continuously and usually not been in the present moment.
In addition to our individual consciousness we are also part of a collective consciousness (CC). In our very individualistic society CC is not mentioned very often and yet this global consciousness is very important and probably is affecting us probably far more than we think or want. Just as Internet is made up of millions of individual sites and as the universe is composed of billion of individual stars CC is made up of billion of ICs from all living beings. There is no Internet without individual site and there is no individual site without Internet. The same can be applied to consciousness: there is no CC without the individual ones and vise versa. Furthermore CC contains all IC components and IC contains all elements of the collective consciousness.
The Buddha taught these 2,500 years ago and called it interconnectivity of all beings. The Dalai Lama called this CC the Streaming Consciousness that has no beginning and no end.
What is the point of all of that?
Like individual consciousness CC can do wonderful things around the world in many ways such as helping, caring and loving. On the other hand and again like the individual one CC can be very destructive with violence, crime, war, racism, homophobia, discrimination, etc. Recent medical findings found that at various degrees all wonderful and dreadful characteristics of our global consciousness can be found in each individual one and vise versa. Did you know that we genetically carry some degree of aggressiveness but this genetic trait is somewhat put in a dormant state for most of us thanks to our education, peer pressure and the influence of society.
Can each individual consciousness and behavior influence the collective one? Maybe when it appears at the right time, the right place and with the right environment. Probably most of the time individual consciousness and personal decision have no effect globally. No one has a clear answer to this question.
As far Zen meditation is concerned.
The fact that Zen meditation during group session is more effective than during solo practice may probably be related to the effect of multiple individual consciousness/mindfulness acting on the collective consciousness/mindfulness on top of course of the surrounding peer pressure. Group practice may create a global mindfulness that is helping everyone involved. This is just a hypothesis
Ven. Ji Gong Sunim.