Brainstorming was developed by Alex F. Osborn in 1939 to enhance the ability of work groups to solve problems creatively. The participants in his early groups called his process "brainstorming" because it seemed to them that they were using their brains "to storm a creative problem and to do so in commando fashion, with each stormer audaciously attacking the same objective." According to David Whetten and Kim Cameron, there are four cardinal principles that govern effective brainstorming processes:

1. No evaluation of the effectiveness of any given alternative is to be undertaken while the group is generating alternatives. Evaluation of alternatives must come at a later stage in the problem-solving process.
2. The leader of the group must place no parameters upon the group regarding what kinds of alternatives or solutions should be suggested; in fact, the team leader should encourage the group to come up with novel ideas...