Despite what the aficionados of CRM may like to think, it was never intended that every operational decisions by the pilot in command should be subject to committee agreement.
No, but it is intended that both have shared and accurate view of the current situation. That is less likely if one pilot makes decisions without involving the other. I would say it is the responsibility of the Captain to ensure that shared and accurate view where possible. Ideally, authority should only come into play when required to maintain adequate safety margins.