If I remember the section of that book correctly, Andrew Grove talks about how you want to handle decision making as a manager. According to Andrew, you want to have folks come to a decision with minimal intervention from you. Part of it is having people feel ownership, another is managing your own political capital. In terms of when you intervene, you should step in and help break ties. You should also be able to ultimately make a decision if the group is unable to do so either because they're taking way too long to deliberate, if their arguments are going full circle, etc.