1. A method for facilitating collaborative decision making, the method comprising: receiving, at a computer system, data representing one or more individual postings and ratings associated with the individual postings, the data associated with a deliberation to make a decision; representing the received data in a hierarchical data structure; aggregating, through the hierarchical data structure, the ratings associated with the individual postings to obtain strength values; facilitating collaborative decision making based on the strength values; and receiving a change associated with the individual postings or the ratings and notifying at least one user of the change, wherein the change is a change of an assumption that an idea is true to an assumption that the idea is false and wherein the notifying is to each user who had supported the idea based upon the assumption that the idea is true; wherein a processor unit coupled to a memory device in the computer system performs the receiving the data, the representing, the aggregating, the facilitating of the decision making and the receiving the change and notifying the users.