how to know if an idea is a good idea

If the idea is well received it doesn't necessarily mean it's a good idea. Goodness needs to be evaluated by consultation until every existing criteria of goodness is fulfilled and then the reasonable assumption would be that it is a good idea. However, continued debate and development of the idea and definition of goodness is also needed taking into account every culture, is needed to ensure it is a probable good idea even in changing times. The idea needs to always be open to questioning to ensure ongoing questioning and improvement. By the laws of nature, stasis is impossible, so continual improvement is the ideal.