Do not change your opinion just because somebody challenges you on that

If you have presented something in a meeting and somebody there refutes your argument, DO NOT accept that easily. You have done some background work, you have some knowledge, you have some expertise, that is why you are presenting that point. Try to clarify the person what you are trying to say. Try to question him on what other information he has, which you might have overlooked. But in any case, do not be subjugated by other immediately. If you do , it shows that you are shallow, your argument doesn’t have any weight.