It really depends on the culture. Being French I do not see it as "duplicity" - it is rather a way to accommodate the reality of life (dumb ideas), their impact

It really depends on the culture. Being French I do not see it as "duplicity" - it is rather a way to accommodate the reality of life (dumb ideas), their impact (make it the lowest for you and for the company) and your comfort. Such white lies help everyone to be on top of their duties - your manager knows that they checked the mark called "evangelize the idea to your team" and you know that you checked the mark "I have provided useful feedback by nodding my head a few times". It stops there and life continues. In an ideal world, we would not need to do any of these because all ideas would be fantastic and everyone would be enthusiastic about them. Unfortunately, I do not live in such a place.