Incorporate challenges, don't protect against them...

Precondition:
Everyone working for a company should be assumed to have a vested interest in its success because, selfishly put, they want the company to SUSTAINABLY make money so they can SUSTAINABLY make money. (Hopefully they also have pride in the work, their team, and the company's impact on the world.)

Theorem:
By working within a company, employees are likely to have as much or more insight into the domain than the average user of their product or service. Therefore, if one employee has an idea and another employee challenges that idea, it is very likely that eventually some portion of your paying customers/users will have a similar reaction or be affected by the raised issue.

Proposal:
When someome challenges an idea, they are not challenging you personally but instead they are helping insure that the idea will improve the company future and will not detract from other ideas. If the idea is one you support, then it is your duty to accept these challenges as a way to collaborate and make the idea that much stronger.

1. You must first try and UNDERSTAND what they see
2. You can communicate your idea differently in the hope that CLARITY will enable them to support your idea
3. You can enlighten them with FACTS you might have that will change their point of view
4. If they still can't see your idea as one they can support, then you should attempt to debate, collaborate, and COMPROMISE until the idea is one that everyone in the conversation can support and go out and sell to others. [Note: this can be bypassed if the person challenging you can agree that your idea doesn't detract from the larger set of ideas and you have the authority to make said decisions. (This is to combat the everyone-can't-be-involved-in-every-decision momentum blocker.)]
   

The fundamental thought here is that people need to stop baking ideas alone in their head (or a mini-sub-group) until they believe it is perfect and then expect the world to accept it as is. Humans are tribal social people and we have different perceptions of what we want. Once you state any idea that you want others to desire and use, you must accept that you don't control it any longer. It must be molded to the needs of the group you expect to utilize it. Anyone that can help you do this will get you a step closer to success.

This is fundamental in usability, marketing, business... even the selection of what to put on your grocery list (if people other than you share in consuming those items).

Summary:
If your employees aren't drinking your Kool-Aid, then why do you expect your customers to do so? If your team doesn't have the passion you do about trying something new, then they aren't likely to support you as a team when you pioneer new paths!

Credit:
This was inspired by some thoughts triggered by Dale Emery's discussion about resistance as a resource and Denise Caron quotes found in this slideset about agile:

Open yourself to critics and take your capabilities to new heights
Don't fall in love with your product, someone will be there to change it, it's a promise