General audience
Sometimes, an organizer must decide if a meeting should be open to all those interested, or restricted to a certain audience. Since restrictions often create animosity, it is better to avoid them if possible.
Meetings with restricted audiences, such as the Gordon Conferences, may be desirable for confidentiality and/or in-depth discussions. To keep bad feelings to a minimum, however, one should be honest about the purpose of ‘closed’ meetings, and the rules that apply. Blackball schemes have a tendency to backfire, sometimes to the point of ostracism of the organizer. As they say, every dog will have his day.
Of course, the difference between ‘open’ and ‘closed’ meetings can be blurred. For instance, when a society raises the convention fee for non-members to prohibitively high levels; or, when someone convenes a conference in a place with limited overnight accommodation, and fills the available rooms with friends.
The weirdest proposal I ever came across requested funds for a special conference. The audience was limited to the number of seats in a small room. And how were the participants to be selected? By inviting everybody interested to submit an application that was to be reviewed by the organizer – who himself had no research funds whatsoever!
Question: Why should anyone pretend a de facto closed meeting is ‘open?’
Answer: In general, public money is easier to get for ‘open’ meetings.
In some fields of research, growing numbers of participants have changed the family atmosphere of the conferences.