How you can support critical thinking and constructive discussion within your team

Every manager should try to get their subordinates to practise critical thinking and discuss constructively among themselves. Only old-fashioned, authoritarian managers believe subordinates should ask no questions, never argue, and do only as they are told. An effective manager, on the other hand, welcomes feedback and to some extent allows subordinates to comment critically and constructively on what is happening in the team and on projects the team is responsible for. How can you encourage critical thinking and constructive discussion in your team, but at the same time avoid perpetual debate and team paralysis?