All ideas face criticism but some ideas succeed. When critics are confronted with the fact that they were wrong their standard response is "I'm glad I was wrong and that we have succeeded!" By joining the winning side a critic becomes a supporter which makes everybody happy going forward. Except it teaches the critic the wrong lesson!
Putting yourself in a position of a critic is a win-win situation. If you're right, you'll be lauded for your wisdom when the idea fails. If you're wrong, you join the winning side and you win again. While the critic wins in any case, the team or the company or the society always looses since not only the critic doesn't create anything but he or she actively undermines efforts of others.
Most ideas are bad and should therefore rightfully be criticized and be prevented in advance before they get a chance to become a reality. So the proper way to handle a critic is not to silence him or her but to make him or her have a stake in his or her criticism. A critic should either commit to the common cause with the rest of the team executing the idea or be excluded from the team altogether for good. In no way should the critic stay on the team or you risk eventual destruction of the team when all the members of the team find out that the most safe and comfortable position is to put themselves in opposition to any change in status quo.