There are three types of arguments you may be using. First is the politically correct argument, in which the biggest issues are not discussed. There is the meeting before the meeting and the meeting after the meeting, but no meeting during the meeting. You focus more on what not to say than on the outcome you want to achieve. Second is the destructive conflict. The one in which everything is personal and emotional. Team members don't listen to one another. The focus is on winning and being right, more than on reaching a better solution. 

The third type, constructive conflict, supports effective and creative teamwork. Nothing is personal. What happens (and is said) here stays here. Everything is on the table. Everyone participates. Agreement is not a mandatory outcome. Aristotle said, "It is the mark of an educated mind to be able to entertain a thought without accepting it."

To conduct this type of conflict, each team member must have three personality traits:

1. Be vulnerable. Ask stupid questions

You must allow yourself to ask stupid questions and propose stupid ideas. For that, you obviously have to trust that others won't make fun of you and, even worse--share your stupid ideas and questions outside the team and the meeting. You never know when a stupid idea or question would give someone else a great idea or, God forbid, would actually not be stupid to start with. Great ideas come from the fringes of knowledge. That, however, is also where the majority of stupid ideas exist. 

2. Be comfortable challenging the others

When you hear a stupid idea or question, you must feel comfortable enough to challenge it. To state that it was stupid. To criticize it, and to provide direct and honest feedback, without the intention of hurting the recipient, but at the same time without having to worry too much about offending them. Your willingness to provide such feedback would allow that person to improve the idea and to improve themselves.

3. Be confident enough to accept feedback

At the same time, you must feel confident enough to accept such criticism without taking it personally or emotionally and attacking back. You must listen to the feedback. You must remember that maybe only 10 percent of it is true, but that 100 percent of it is true in perception. You have to see the other side's perspective, and you must focus on building on that feedback, rather than letting it destroy you. 

There are two main prerequisites for those three traits: trust between team members and the willingness of each member to exercise those traits.