Whenever someone gets an idea in their head they start filtering out evidence that contradicts that idea. This idea is called confirmation bias, people start looking for evidence that confirms their current idea and neglecting evidence that challenges it. There's no way to completely beat a bias, but something that helps me is reframing the question.
The first question that comes is normally "Can". Can it be? This leads to looking for evidence that confirms the idea.
A different perspective is to reframe the question to "Must". Must it be? This challenges the default setting, and starts asking for evidence that rejects the idea.
A third perspective is refreaming the question to "Should". Should it be? This question starts to challenge the moral and the rational parts of the brain.
When you've got a great new idea try to test it by reframing with "can", "must", "should".