Make the best case you can for adopting course of action X to solve potential problem Y. Then step back and let the person in charge make the decision. My rule

Make the best case you can for adopting course of action X to solve potential problem Y. Then step back and let the person in charge make the decision. My rule of thumb is two 'No' answers. It goes like this: Present affirmative reasons why direction X is the right choice. Try to focus on the benefits of X rather than pointing out the flaws in the current plan. If the response is no, I'll try to address any concerns regarding X. If the response is still no I leave it alone. I've found that if you continue past this point it becomes an argument. Now you're challenging the groups ability to proceed after making a decision. Once that occurs your opinions are an impediment to the groups progress. Note: Perspective is worth 80 IQ points. The team could be basing the decision on factors you aren't aware of. The world is seldom simple enough to present one 'best' answer to a given situation. EDIT: No they aren't "all against you because you're so much smarter than them". Seeing this sentiment in some of the comments. Trust me this doesn't happen. For every one real instance of this, there are 100 instances of condescending engineer who is just parroting the technology fad of the day. Or is an architecture astronaut. To anyone who feels this way regularly ask yourself "How many times have I felt like this? In school? In college? At job 1? At job 2?" Either the world is wall to wall jerks, or you're the jerk.