Working in teams is a seriously important skill. Let's consider why that is. If you could do everything on your own - sweet. But that's kinda rare, because you have a limited amount of time, and a limited set of skills you can bring into a project. So - in order to give a project more resources, you need a team.

So, you get into a team, and then spend more time arguing about stuff than getting it done. Why exactly is that? Here's my take:

• People are fighting for control over the project, or their own little sections.
• One person is arguing for something that will benefit them personally.
• Two people just don't like each other.
Firstly, understand that there is one good thing about this situation - people would only argue if their work was important to them. When they stop arguing and drift into apathy, that's even more serious.

So let's examine how we might solve some of these things.

• You, as the manager, get to divvy up the responsibilities. If you ensure those divisions are clear, you can avoid some of the conflicts over responsibilities. Oh - by the way - that's not as easy as it sounds.
• People in teams argue for their self-interest, sure. It's actually really hard to argue for a conclusion that actively penalises yourself, for example by taking responsibility away from you. Best way to solve this is "alignment", or making sure that everyone trusts each other, and is focused on the overall goal rather than their own areas. This conflicts - slightly - with the first point.
• Personality clashes happen all the time. This is where you need to step in - you need to bend your personality to match the people you're talking to. If you're talking to someone who's up tight and organised, be that. If you're talking to someone who likes to go and get stuff done on their own, tell them what you need and don't bother them until you need the answer. And so on.