That is a committee, not a team.

It depends on the situation: do team-members come from the same culture and/or background?
I can point out it does not seem to be a team, for no one has authority; it seems to be some sort of committee, in which case I recommend you to read the following article (it may be based on history, but it is to the point – committees): Project Management and Committees

Basically, you need some sort of authority, therefore you should try convincing them of this basic necessity.