One of the developers of my team is causing a bit of "stress" inside the team. We are organized in an Agile team (we use Scrum), and we meet regularly, both for the various "ceremonies" (estimating stories, for example) and for design meetings.
The team is self-organizing: design of stories is not "imposed" (I guide and steer them, and do the high level architectural design, but I let them choose the best approach at a code level), so there is often discussion and whiteboard schemes and the lot.
This dev, despite being junior (actually, the least experienced in the team), always has an opinion. And this is good, I like it: it brings ideas and potential issues in the design. But the fact is that even when he proposes something that is clearly bad (clearly = everyone else sees that it is bad, from experience), he still keeps advocating his position, believing he is right.
I (and others) have really to convince him, proving, presenting evidence. All good, as he learns and we enforce (and test) our assumptions, but this happens constantly, on every detail.
The problem is that what could have been a 1 hour discussion becomes longer and longer, and everyone else becomes tired and stop interacting.
I do not want to exclude him from the design process (I already tried to limit the sessions in which he is involved; he complained but it was an improvement for all the others), and when I can tell the team is really tired I just impose my decision (something on the lines "No, we are going to do it this way, trust me, we move on").
Do you think this is acceptable, stopping him and imposing my decision? How can I improve the situation without "losing" him, cutting him off (or acting in a way that will lead him to cut himself off the team)?
I have found a couple of related question. Related, but different:
In that case, the person who believes is always right is the team architect. My case is very different (and is not covered by the answers) as the developer is both junior to me and I am his team leader.
Another, closer question: How to deal with team member who is picking argument always instead of understanding the point?
But again not really related. He does not look for a fight, nor he is offending (at least, I do not feel offended).