Ideas Need to be Challenged

Coming out with ideas and solutions can be exciting. Especially if we have come out with great ideas that seem to solve our problem. We understand the problem because we defined it in Step2. From that, we have come out with a few good ideas in Step3. In fact, this can be an opportunity because we may have come out with something better than the original which failed or was creating problems. We may not only have found a solution to our problem, it may even improve on what we had before. We have come to the point where we now need to choose one of these ideas to do, Step4. And Step4 requires that ideas that came in Step3 be scrutinized and challenged. 
This can be hard, especially if we are working on our own. Each of the possible solutions we came up with is great and we can't see any other way to solve it. We need to choose one but sometime we become stuck. We don't or simple can't choose one of the possible solutions to do. This can stop our problem solving effort right in it's track. We know we have to choose but we like them all so much that it is hard let go any of them. 
This reminds me of something that happened to me in the late 90s. I was asked about what would be the next thing in PC desktop interfaces. We had just begun getting used to windows and the concept of Start button. I thought that because graphic cards with 3D were getting cheaper and starting to appear almost everywhere, the next step in PC desktop interfaces would take advantage of that. I proposed the future PC desktop environments would be in 3D. If Microsoft requires PCs to have 3D capabilities, PC makers would then make it a standard. This is good for them because it would make people to want new PCs. It happened once before with CD-ROM drives, so why not 3D graphic cards?
My design was based on the concept that the desktop would exist in a 3D world. Application windows would "float" in the air above a horizon. By moving within the 3D world, you would move and zoom in and out of the windows. For example, if you are working on a spreadsheet and you want to see another document, you can "move backward". This would make the spreadsheet window smaller (because it's "further" away) and it's contents smaller but still visible. Now you can open a document at the "normal" size and cut and paste in between them as you would normally do.
A horizon on the bottom of the screen would create the idea of land. It would move according to your movements within the world. I thought that it would also have features like hills and bodies of water create the idea of unique places within the 3D world. These places could be used to group windows. For example, a horizon with a lake is where we could do graphics work while a horizon with a cityscape where I could put my spreadsheets windows.
So what's the point I'm trying to make here?
I thought of all that in the space of about 15 minutes. In fact, it took me longer to type it out here than when I came out with it. I thought it was great. But once I talked about it with other people, we found a lot of  problems. While everybody agreed that 3D hardware would be standard on all PCs, not many agreed that the desktop should go 3D.
Firstly, 3D displays at the time had really low resolutions. That means the 3D graphics cards at the time were not powerful enough to draw 3D at good desktop resolution. The windows and icons would look blocky. Secondly, although the concept was cool, people didn't like squeezing in more windows in one screen. Even when people could do that, they preferred a second screen to put more windows in. Thirdly, there would be problems when trying to quickly move within the 3D world with a mouse. In 3D games, you would need both a mouse and a keyboard to do that. You would need a special mouse with about a thousand extra buttons. In fact, to this day, not all PCs have 3D capabilities. That was how bad the ideas was.
My point is that although my idea sounds smart and cool inside my head, I discovered there were many problems with it once I shared it with other people. The more people I shared it with, the more varied the responses were. I didn't agree with all of them but I did try to take their position to see if I thought they were valid. Sometimes by doing this, I could see something different than they did.
When working in a group, we need to share the idea with others who can challenge it. This means that they will try to take the idea apart. They do so because we want to find out together whether the idea has problems itself. Some people only want to listen to themselves. They would share ideas among people who think similarly, creating a echo chamber effect. In this chamber,  ideas were being amplified without actually being scrutinized. If combined with exclusion, it would be even worse. Exclusion is the attitude that "if it doesn't work for you then it's not for you". This is often backed up with the attitude of "we know better" when dismissing comments about the idea.
Challenging ideas and possible solutions from Step3 is a key part of doing Step4. It helps understand the that particular idea and it good and bad points. This way, when we choose one solution to do in Step5, we are prepared not only for the solution's positive returns but also other problems that may come up.