How did the Second Vatican Council address the relationship between papal primacy and the bishops?

The Second Vatican Council addressed the relationship between papal primacy and the bishops primarily through the doctrine of episcopal collegiality, as articulated in the dogmatic constitution Lumen gentium (1964).1

While the Council reaffirmed the teachings of Vatican I regarding papal primacy and infallibility, it emphasized that bishops are not merely vicars of the Roman Pontiff. Instead, the Council taught that:1

• Proper Authority: Bishops exercise an authority that is proper to them, as they are the successors of the apostles and "vicars and ambassadors of Christ" in their own right.1
• The Apostolic College: Just as St. Peter and the apostles formed one apostolic college, the Roman Pontiff and the bishops are joined together as a college.1
• Supreme Power: This college, with the Roman Pontiff as its head and never without him, serves as the subject of supreme and full power over the universal Church.1

By emphasizing this collegial structure, the Council sought to balance the role of the papacy with the inherent authority of the episcopate, viewing the exercise of supreme authority as something that can occur both personally by the pope and in a collegial fashion by the whole episcopate.12